Johnson Controls LX-HPUL-1, LX Series User Manual

LX Series Heat Pump Unit Controller

User’s Guide

Code No. LIT-12011484

Issued June 22, 2009

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Feature Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Sensor Configuration Wizard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Control Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

LonMark Functional Profile. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Units in LONWORKS Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Language Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Selecting a Measurement System or Selecting a Language . . . . . . . . . . . . . . . . . . . . . 16

Heat Pump Unit Controller Installation Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

10k Ohm or Digital Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Analog Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4 to 20 mA Analog Input, Externally Supplied . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Sensors and Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Auxiliary Alarm Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Bypass Contact Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Coil Differential Pressure Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Coil Frost Contact Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Discharge Temperature Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Emergency Contact Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Fan Speed Selector Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Fan State Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Mode Selector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Occupancy Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Outdoor Temperature Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

1LX Series Heat Pump Unit Controller User’s Guide

Pump State Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Refrigerant Temperature Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Setpoint Offset Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Space Humidity Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Space Temperature Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Water Temperature Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Window Contact Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Analog Output Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Digital Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Staged Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Output Selections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Fan Speed 1 - 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Heating Outputs 1 - 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Cooling Outputs 1 - 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Reversing Valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Humidifier and Dehumidifier Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Mode Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Network Variables Used for Mode Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Occupied Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Starting Occupied Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Ending Occupied Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Unoccupied Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Starting Unoccupied Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Ending Unoccupied Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Bypass Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Starting Bypass Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Ending Bypass Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Standby Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Starting Standby Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

LX Series Heat Pump Unit Controller User’s Guide2

Ending Standby Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Slave Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

State Selection and Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Supervisory Control and Scheduling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Calculating the Space Temperature Setpoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

The Effect of nviSetPoint on the Active Setpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

The Effect of a Setpoint Offset on the Active Setpoints. . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Humidity Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Defrost cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Cooling State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Mechanical Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Cooling Demand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Cooling Output Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Ending the Cooling State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Heating State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Heating Demand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Heating Output Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Cooling Outputs Used to Heat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Ending the Heating State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Night Purge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Morning Warm-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Fan Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Terminal Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Heating Terminal Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Cooling Terminal Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Networking Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Slave Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Load Shedding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Setting Up Network Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Network Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

LX Series Heat Pump Unit Controller User’s Guide 3

Optimum Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Requirements for Optimum Start. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Emergency Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Emergency Initiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Normal Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

The PID Loop. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Proportional . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Integral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

How It Is Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Derivative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Dead Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Alarm Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Alarm Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Alarm Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Alarm Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Heartbeat Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Disconnect Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Emergency Mode Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

User-Set Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Setting up the Heat Pump Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Persistent Network Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Setting Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Input Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Heartbeat (Max Send Time). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Throttle (Min Send Time). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Delta Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

LX Series Heat Pump Unit Controller User’s Guide4

Override Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Default Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Sensor Hardware Properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Input Signal Interpretation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Signal Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Thermistor Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Offset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Max Value, Min Value. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Reverse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Increment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

TransTable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Get Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Configuring an Input Represented as a L

ONMARK Object . . . . . . . . . . . . . . . . . . . . . . . 66

Output Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Output Signal Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Configuring an Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Creating a Functional Block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Configuring an Output Represented as a Functional Block. . . . . . . . . . . . . . . . . . . . . . . . . 70

Heating-Cooling Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Fan-Valve Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

PID Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Alarm Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Space Temperatures and Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Discharge Temperature and Auxiliary Alarm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Fan Alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Pump Alarm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

General Settings Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Radiation Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Options Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Optimum Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

LX Series Heat Pump Unit Controller User’s Guide 5

Frost Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Defrost Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Humidity Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Network Input Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Heartbeat Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Network Output Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Object Manage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Object Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Communication Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Electrical Fault . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Out of Limits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Disabled. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

In Alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

In Override. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Out of Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Network Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

nviApplicMode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

nviCoilDiffPress. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

nviDischargeTemp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

nviEmergCmd. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

nviExtCmdOutputx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

nviFanSpeedCmd. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

nviFanState. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

nviHotWater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

nviOccCmd & nviOccManCmd. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

nviOutdoorTemp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

nviPumpState. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

nviRefrigTemp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

nviSetPoint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

nviSetPtOffset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

LX Series Heat Pump Unit Controller User’s Guide6

nviShedding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

nviSlave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

nviSpaceRH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

nviSpaceTemp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

nviWaterTemp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

nvoCtrlOutput. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

nvoDischargeSetPt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

nvoEffectSetPt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

nvoFanSpeed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

nvoHPalarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

nvoHPstate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

nvoHwInput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

nvoOccState. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

nvoSpaceTemp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

nvoTerminalLoad. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

nvoUnitStatus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Standard Network Variable Types (SNVT). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

SNVT_hvac_emerg (103 HVAC Emergency Mode). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

SNVT_hvac_mode (108) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

SNVT_hvac_status (112). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

Alarm State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

SNVT_lev_percent (81) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

SNVT_occupancy (109) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

SNVT_switch (95). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

Switch Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

SNVT_temp_p (105) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

SNVT_tod_event (128) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

LX Series Heat Pump Unit Controller User’s Guide 7

LX Series Heat Pump Unit Controller User’s Guide8

LX Series Heat Pump Unit Controller

User's Guide

Introduction

Feature Description

The LX Series Heat Pump Unit (HPU) Controller integrates into a LONWORKS®
network for the control of almost any heat pump unit due to its wide range of
output types and LONMARK® certification.

The LX Series Heat Pump Unit Controller controls the following equipment:

• four stages of mechanical heating or cooling

• modulating heating or cooling valves

• reversing valves

• floating valves for heating or cooling

• pump for geothermal application

• three fan speeds or variable speed fans

• humidifier and dehumidifier
The Heat Pump Unit Controller has five digital outputs supplying 1.0 ampere at

24 VAC. These outputs produce digital or Pulse Width Modulated (PWM) signals.
Also, two tri-mode analog outputs are on the circuit board. These outputs provide

the following signals:

• linear signals over a 0 to 10 VDC range

• 10 VDC digital or PWM signals

• digital signal of 60 mA at 12 VDC
The Heat Pump Unit Controller has six inputs, each capable of one of 18 possible

input types. Inputs have 12-bit resolution and are configured entirely by software.
For easy maintenance and installation, the controller is equipped with wizard

connectors that can accept flat cable or wires. The controller uses a TP/FT 10;
78 kbps network configuration.

The information in this guide helps you to set up the Heat Pump Unit Controller,
understand the operation of the device, and troubleshoot problems. Information is
organized to follow the Heat Pump Unit Controller configuration wizard menu.

LX Series Heat Pump Unit Controller User's Guide 9

Sensor Configuration Wizard

The Heat Pump Unit Controller incorporates the Johnson Controls® sensor
configuration wizard. The wizard provides powerful and simple configuration
tools for the hardware inputs. You can only select digital or analog inputs through
the software. You do not need to move any circuit board jumpers.

Analog input signal types–resistive, voltage, current–are selected in software
without hardware jumpers. Built-in conversion tables are provided for a large
number of thermistors or other sensor types. You can easily create custom
conversion tables by setting the offset, minimum, and maximum values in one
dialog box for the input.

The sensor configuration wizard also provides direct access to network properties
of the analog or digital input including the Standard Network Variable Type
(SNVT), Heartbeat, Send on Delta, Override, Default Value, and Throttle settings.
All of the input features are in one place; therefore, it is not necessary to switch
back and forth between screens to fully configure an input.

The sensor configuration wizard provides warnings of configuration errors as they
occur, allowing you to correct mistakes quickly.

The sensor configuration wizard is accessible in the LX-HPUL wizard view of an
LX-HPUL device in FX Workbench. Each hardware input is represented by a
separate LONMARK object. To configure each input, select the desired hardware
input on the left side of the LX-HPUL wizard view and Sensor Configuration in
the Wizard column of the view and click the Launch button. The sensor
configuration wizard opens. Through use of the wizard, you can configure network
inputs not directly controlled by the HPU Controller.

Control Features

The Heat Pump Unit Controller provides Proportional plus Integral plus Derivative
(PID) loops for advanced control of humidity, discharge temperature, and space
temperature. Each PID loop has an individual, configurable dead band; and,
provides gain and time adjustment for the integral and derivative terms, and gain
adjustment for the proportional term.

Humidification and dehumidification sequences provide the Heat Pump Unit
Controller with the ability to maintain space humidity at the desired level. Defrost
cycles are started by the HPU when the differential pressure is high, or by a
sequence in conjunction with the refrigerant temperature sensor. Space
temperature control is done with a PI loop only, but the presence of the derivative
term provides the HPU Controller with the ability to precisely adjust space
temperature. Precision adjustment ensures both increased comfort and savings.

Often associated with air handlers, the HPU Controller provides advanced control
settings including Optimum Start and load shedding.

LX Series Heat Pump Unit Controller User's Guide10

The Optimum Start function maintains statistics that enable the Heat Pump Unit
Controller to predict the warm-up or cool-down time period needed to make the
building ready for occupancy. The precise Optimum Start period is calculated
every day using the current outdoor air temperature.

LONMARK Functional Profile

The LX Series Heat Pump Unit Controller uses the LONWORKS protocol. The Heat
Pump Unit Controller is LONMARK certified for interoperability on any
LONWORKS network. The controller is set up through its own configuration wizard
and through the Sensor configuration wizard. Use FX Workbench to install the
device onto the network and bind the network variable connections.

Figure 1 shows the Heat Pump Unit Controller meets the LONMARK standard by
providing the network variable inputs, network variable outputs, and configuration
properties specified by the profile. In addition, the Heat Pump Unit Controller
provides extra network variable inputs and outputs. These extra variables provide
greater flexibility and a number of functions than required in the profile.

For example, functions determined by the network variables include slaving the
controller to another unit through nviSlave or enabling the controller to act as the
master node through nviUnitStatus.

LX Series Heat Pump Unit Controller User's Guide 11

LX- H PUL- 1 HeatPump

Object Type # 8051

nviSpaceTemp

SNVT_temp_p

nviSetPoint

SNVT _temp_p

nviFanSpeedCmd

SNVT_switch

nviApplicMode
SNVT_hvac_mode

nviSetPtOffset

SNVT _temp_p

nviWaterTemp

SNVT_temp_p

nviDischargeTemp
SNVT_temp_p

nviRefrigTemp

SNVT_temp_p

nviSpaceRH

SNVT_lev_percent

nviEmergCmd

SNVT_hvac_emer

nviFanState

SNVT_ switch

nviPumpS tate

SNVT _switch

nviCoilDiffPress

SNVT_press_p

Mandatory

Network

Variables

Optional

Network

Variables

nvoFanSpeed

SNVT_ switch

nvoTerminal Load

SNVT_lev_percent

nvoDischargSetPt

SNVT_temp_p

nvoSpaceTemp

SNVT _temp_p

nvoEffectSetP

SNVT _temp_p

nvoOc cState

SNVT_ occupancy

nvoUnitStatus

SNVT_hvac_status

Configuration Properties

Occ. Temperature Set Points(mandatory)

Maximum Send Time (mandatory)

Minimum Send Time (optional)

nviSheddi ng

SNVT_switch

nviHotWater

SNVT_switch

nviSlave

SNVT_lev_percent

nviO utdoorTemp

SNVT_temp_p

nviO ccCmd

SNVT_xx

nviO ccManCmd

SNVT_ occupancy

Manu facturer

Network

Variables

Manufacturer Configuration Properties

Please see the manual for details.

Wizard for configuration provided.

nvoCtrlOutput1

SNVT_ switch

.
.
.

nvoCtrlOutput7

SNVT _switch

Figure 1: LX Series Heat Pump Unit Controller:

ONMARK Objects and Network Variables

L

LX Series Heat Pump Unit Controller User's Guide12

The HPU Controller also has network inputs that permit the use of outside
enthalpy sensors and space enthalpy sensors. These inputs provide better
calculation of the cooling or heating effect of the outside air upon the conditioned
space.

The input object has configurable conversion tables and hardware properties in the
area marked Manufacturer Configuration Properties. Choose from a list of
standard thermistors to select conversion properties and create your own custom
tables. Hardware properties configuration allow you to modify your input from the
software object. Figure 2 shows the output and input objects.

nviExtCmdOutputx

SNVT_switch

LX-HPUL- 1 Hardware Output

Obj ect T yp e #3

Mandatory

Network

Variables

Configuration Properties

Maximu m Rec e i ve Time (optional)

Override Value (optional)

Manufacturer Configuration Properties

Object Major Version
Object Min or Version

Output Signal Conditioning

PWM Period

Hardware Properties

Default Value

Figure 2: Output and Input Objects

LX-HPUL-1 Hardware Inpu t

Object Type #1

Mandatory

Network

Variables

Configuration Properti es

Offset (optional)
Maximum Range (optional)
Minimum Range (optional)

Minimu m Send Delta (optional)
Minimum Send Time (optional)

Maximu m Send Time (optional)

Override Value (optional)

Manufacture r Configuration Properties

Object Major V ersion

Object Minor V ersion

Output Signal Conditioning

PWM Period

Hardware Properties

Default Value

nvoHwInputx

SNVT_xxx

LX Series Heat Pump Unit Controller User's Guide 13

The node object displays the nvoHPstate and nvoHPalarm variables as
manufacturer’s variables. The node objects provide information about the alarm
conditions in the Heat Pump Unit Controller and about the operating state of the
device (Figure 3).

LX-HPUL-1 Node

Obj ect Typ e #0

nviRequest

SNVT_obj_request

Mand ator y

Network

Variables

Optional

Network

Variables

Configuration Properties

Location (optional)
Device Major Version (optional)
Device Minor Version (optional)

Manu facturer

Network

Variables

Manufacturer Configuration

Properties

Maximum Send Time

nvoStatus

SNVT_obj_status

nvoFi leDirectory

SNVT_address

nvoHPs tate

SNVT_state _64

nvoHPal arm

SNVT_state _64

Figure 3: Heat Pump Unit Controller Node

Units in LONWORKS Networks

Note: Use this section if you are using the Imperial System of measurement.
The Imperial System and the International System (SI) are the two main

measurement systems used today. Table 1 compares Imperial units and SI units.

Table 1: Comparing Imperial and SI Units

Imperial Units SI

inch centimeter
yard meter
mile kilometer
degrees Fahrenheit degrees Centigrade/Celsius

LX Series Heat Pump Unit Controller User's Guide14

The LONWORKS network and Echelon® SNVTs are based upon SI units. This
basis creates some unavoidable problems in data conversion if you are using
Imperial Units.

The LX-HPUL view in FX Workbench and other utilities provide some automatic
conversion between SI and Imperial units. However, these are not ideal
conversions because a whole number in one system becomes a long decimal
fraction in the other. For example, 72°F is approximately equal to 22.22222°C.

Value is written in

Imperial Units.

Data is displayed

for monitoring in

Imperial Units.

Value is translated

to SI units.

Value is rounded.

Value is stored

in SNVT.

Value is read

from SNVT.

Value is rounded.

Value is translated

to SI units.

Units

Figure 4: Imperial Units in the LONWORKS Network

The values created by converting Imperial to SI or SI to Imperial are subject to
rounding errors. If you enter an Imperial value into a LONWORKS SNVT by using
the HPU Controller configuration wizard, the value is converted, then rounded and
written to the SNVT . When you want to monitor the SNVT, the value must be read
from the SNVT, converted, and rounded again before it is displayed. Due to the
two conversions and two rounding operations, the value may differ slightly from
what you originally entered (Figure 4).

The same process and resulting rounding error applies to Standard Configuration
Property Types (SCPTs).

Instructions for changing or modifying the units of measure used on your computer
are provided in the Selecting a Measurement System or Selecting a Language
section.

Language Selection

The following may require you to change your language settings:

• You changed your regional settings by selecting a different region in the
Regional and Language Options dialog box.

• You work on a site that is in a linguistic region other than your own.

LX Series Heat Pump Unit Controller User's Guide 15

• You are dissatisfied with the language displayed on program menus and dialog
boxes.

You can change your language settings in the Advanced tab of the Regional and
Language Options dialog box. Instructions are provided in the Selecting a
Measurement System or Selecting a Language section.

Selecting a Measurement System or Selecting a Language

To select units of measurement or to select a language:

1. In Microsoft® Windows XP® Operating System, click Start > Control Panel.
The Control Panel appears.

2. In the Control Panel, open Date, Time, Language, and Regional Options.

3. Under the list titled Pick a Task, select and open the second item: Change the
format of numbers, dates, and times (Figure 5).

Figure 5: Date, Time, Language and Regional Options Screen

LX Series Heat Pump Unit Controller User's Guide16

4. Select your language region from the drop-down list. The number, time, and

date formats fill automatically (Figure 6).

Figure 6: Regional and Language Options

5. In the Number box, verify the number format uses a decimal point to indicate

numerals representing values less than 1. For example, use 123,456,789.00, not
123 456 789,00. You must use a decimal point for the correct display of

numerals.

6. In the Regional Options dialog box, click Customize.

LX Series Heat Pump Unit Controller User's Guide 17

7. Click on the drop-down arrow next to the box labeled Measurement system,
and select Metric (Figure 7).

Figure 7: Customize Regional Options

8. Verify the Decimal symbol box contains a decimal point. If the Decimal
symbol box does not contain a decimal point, select the symbol in the box and
click Apply.

9. Click OK.

10. Click the Advanced tab and choose a language region by selecting from the
drop-down list. Verify the correct language appears on program menus.

11. Click OK.

You have now set the units to appear in the LX-HPUL view in FX Workbench. If
you select to have Imperial units appear, remember that the SNVTs still use SI
units. If you are viewing the data in Imperial units, you are viewing a converted
rounded value.

LX Series Heat Pump Unit Controller User's Guide18

Heat Pump Unit Controller Installation Overview

Figure 8 shows one possible installation of the Heat Pump Unit Controller. Inputs,
outputs, heating, and cooling units have been marked.

Note: Not all possible sensors appear.

LX-HPUL- 1 Installation Overview

Heat Pump Enclosure

Intak e Air

Filte r

3 Fan Speeds

Co o ling

Heat Pump Enclosure

Humidifier

Heating

DATOAT

Discharge

Air

Window contact

Occupancy

Conditioned Space

Sensor Symbols

Humidity
Temperature

Digital Input

Setpoint Offsett

Temperature

Humidity

OAT Outside Air Temperature
DAT Discharge Air Temperature

Figure 8: Possible HPU Installation

Inputs

The Heat Pump Unit Controller has six universal inputs. You can use the HPU
Controller Configuration wizard to configure universal inputs. There are two
possible configurations for universal inputs:

• digital inputs or 10k ohm resistance inputs

• analog inputs sensing either current or voltage
Note: As the Heat Pump Unit Controller can connect to a maximum of six

sensors, you may want to connect some sensors using the L
network. All valid network inputs have priority over hardware inputs.

ONWORKS

10k Ohm or Digital Input

The universal input, when configured as a 10k ohm or digital input, accepts a 10k
ohm resistance input or a digital input such as a switch (cold contact).

LX Series Heat Pump Unit Controller User's Guide 19

The 10k ohm resistance range accommodates 10k ohm thermistors used in space
temperature sensors or duct temperature sensors, or 10k ohm potentiometers used
as setpoint offsets.

Use the conversion table for resistance input of more than 10k ohm. The digital
range accommodates the occupancy contact, bypass switch, and window switch.

See Figure 9 for wiring information regarding both digital and 10k ohm resistance
inputs.

LX-HPUL-1

1

I

–

++++++

Both inputs are configured as 10k ohm or
dig ita l in puts. Configuration can be done in
either the LX HPUL-1 wizard

Figure 9: 10k Ohm or Digital Input

I

3

I

2

4

I

I

I

5

6

––

Thermistor

10k Ohm

Contact

NC

NO -

LX Series Heat Pump Unit Controller User's Guide20

Analog Inputs

Analog inputs include current inputs with a range of 4 - 20 mA, and voltage inputs
with a range of 0 - 10 VDC.

4 to 20 mA Analog Input, Externally Supplied

Current inputs require a power supply either on the sensor or wired in series with
the sensor. To construct the current input, place a 500-ohm 0.25-watt resistor
across the Heat Pump Unit Controller’s input terminals. See Figure 10 and
Figure 11.

LX- H PUL-1

1

I

++++++

I2I3 I

–

4

5

I

––

6

I

1
8

0

Resistor:

500

¼

Ω −

Watt

Internal 24 VDC

power supply

4 – 20 mA

–

+

Controller source

output 4

Sensor

Ω=ohm

– 20 mA

Figure 10: Sensor Powered Analog Input

LX-HPUL-1

1

I

–

++++++

Resistor:

500

VDC

24

Ω −

–
+

3

I2I

¼

Watt

4

I

––

4 – 2 0 mA

5

I

I

6

1
8

0

Senso

r

–

+

Figure 11: Externally Powered Analog Input

Sensors and Switches

The following sensors and switches can be connected to the Heat Pump Unit
Controller.

LX Series Heat Pump Unit Controller User's Guide 21

Auxiliary Alarm Input

This input is used to relay an alarm from an external device onto the building
network.

Preferred SNVT types: SNVT_amp, SNVT_amp_ac, SNVT_amp_f,
SNVT_lev_disc, SNVT_lev_percent, SNVT_switch, SNVT_temp_f,
SNVT_temp_p.

Bypass Contact Input

A switch closure on the bypass contact input causes the Heat Pump Unit Controller
to enter occupied mode for the period of time set as the bypass time. However, the
Heat Pump Unit Controller must be in unoccupied or standby mode.

Preferred SNVT types: SNVT_lev_disc, SNVT_occupancy, SNVT_switch.

Coil Differential Pressure Input

The differential pressure is read on each side of the solenoid valve. On a high
differential pressure, the Heat Pump Unit Controller starts the defrost cycle.

Preferred SNVT types: SNVT_press_f, SNVT_ press_p.

Coil Frost Contact Input

If the Heat Pump Unit Controller is in operation, a switch closure on the coil frost
contact causes the Heat Pump to start a defrost cycle.

Preferred SNVT types: SNVT_lev_disc, SNVT_switch.

Discharge Temperature Input

Use the discharge temperature input to maintain the discharge air temperature
between the minimum and maximum discharge air temperature.

A linear equation between the minimum and maximum discharge air temperature
and the space PID loops determines the discharge setpoint. During a high heating
demand, the discharge setpoint moves to its maximum temperature. Conversely,
during a high cooling demand, the discharge setpoint moves to its minimum
temperature. The discharge temperature setpoint can be viewed from
nvoDischargSetPt.

Preferred SNVT types: SNVT_temp, SNVT_temp_f, SNVT_temp_p.

Emergency Contact Input

A switch closure on this input causes the HPU Controller to begin emergency
operation.

Preferred SNVT types: SNVT_lev_disc, SNVT_occupancy, SNVT_switch.

Fan Speed Selector Input

Fan speed selector provides the Heat Pump Unit Controller with an ability to select
up to three different fan speeds.

LX Series Heat Pump Unit Controller User's Guide22

Preferred SNVT types: SNVT_lev_disc, SNVT_occupancy, SNVT_switch.

Fan State Input

The fan state input detects whether one of the three fan speeds is ON or OFF . If the
fan state input does not correspond with one of the fan outputs for a period of time
(known as alarm delay), then an alarm becomes active. If the fan state input is
OFF, while one of the fan outputs is ON, then equipment requiring air circulation
remains OFF or does not modulate.

Note: All outputs except for the fan disable when the fan state is OFF.
Preferred SNVT types: SNVT_amp, SNVT_amp_ac, SNVT_amp_f,

SNVT_lev_disc, SNVT_lev_percent, SNVT_switch.

Mode Selector

Mode Selector enables selection of different modes of operation by means of an
analog signal, such as resistance, voltage, or current input.

Modes of operation available from this input are auto, heat, cool, fan only, and
OFF. Table 2 describes the modes of operation.

Table 2: Modes of Operation

Mode of Operation Description

Auto Operates according to its setpoints and scheduled occupancy states.

The HPU controls heating, cooling, duct pressure, and the fresh air
damper according to the setpoints and the configuration properties you
enter. The controller switches between unoccupied, occupied, standby,
and bypass modes according to its schedule and the occupancy and
bypass contacts if these contacts are present.

Heat Operates according to the heating setpoints in heating mode only. The

heating setpoint may change as the controller changes scheduled
states. Cooling mode is unavailable.
The fan is ON when heating is ON. The fan is OFF at other times unless
configured as ON during occupied periods.

Cool Operates accordin g to the cooling setpoints in cooling mode only. The

Fan Only Configures the fan ON during the scheduled occupied state. Heating

OFF Disables the control loop to OFF. All outputs are in the OFF state.

cooling setpoints may change as the controller switches scheduled
states. Heating mode is unavailable.
The fan is ON when cooling is ON. The fan is OFF at other times unless
configured as ON during occupied periods.

and cooling is not available. Fan configuration is found on the Fan-V alve
screen of the Heat Pump Unit Controller configuration wizard.

Preferred SNVT types: SNVT_hvac_mode.

Occupancy Input

A switch closure on this input sets the HPU Controller to occupied mode. The
HPU Controller exits occupied mode when the switch is opened. Unless the
controller is in bypass mode, the occupied contact does not function if the network
variables nviOccCmd and nviOccManCmd are set to unoccupied.

Preferred SNVT types: SNVT_lev_disc, SNVT_occupancy, SNVT_switch.

LX Series Heat Pump Unit Controller User's Guide 23

Outdoor Temperature Input

The outdoor temperature input depends upon the availability of the refrigerant
temperature input to determine whether a defrost cycle is needed. It can also be
used for the Optimum Start statistic.

Preferred SNVT types: SNVT_temp, SNVT_temp_f, SNVT_temp_p.

Pump State Input

The pump state input detects if the pump is ON or OFF. If the pump state input is
OFF, and the pump output is ON during an alarm delay, then an alarm becomes
active. If the pump state input is OFF while the pump output is ON, cooling stages
1 - 4 (that require water or glycol circulation) remain OFF.

Note: This pump state only accepts a dry contact input.
Preferred SNVT types: SNVT_amp, SNVT_amp_ac, SNVT_amp_f,

SNVT_lev_disc, SNVT_lev_percent, SNVT_switch.

Refrigerant Temperature Input

The refrigerant temperature sensor determines if the Heat Pump Unit Controller
starts the defrost cycle. To perform this sequence, the controller also requires the
outdoor air temperature.

Preferred SNVT types: SNVT_temp, SNVT_temp_f, SNVT_temp_p.

Setpoint Offset Input

Setpoint offset input provides a means of varying the setpoint during occupied and
standby modes. The value from setpoint offset is added to the pair of active
setpoints. See the Calculating the Space Temperature Setpoint section.

Preferred SNVT types: SNVT_temp, SNVT_temp_diff_p, SNVT_temp_f,
SNVT_temp_p.

Space Humidity Input

The space humidity sensor provides the Heat Pump Unit Controller with the space
relative humidity. Relative humidity can be used as an input to the humidity
control PID loop.

Preferred SNVT types: SNVT_lev_percent.

Space Temperature Input

The Heat Pump Unit Controller uses the space temperature to control heating or
cooling operations. One of the following inputs must be present for the HPU
Controller to function:

• space temperature

• nviSlave

LX Series Heat Pump Unit Controller User's Guide24

The space temperature sensor can be a 10k ohm thermistor, or it can provide a
voltage or current input to the board.

Preferred SNVT types: SNVT_temp, SNVT_temp_f, SNVT_temp_p.

Water Temperature Input

The Heat Pump Unit Controller provides heating or cooling through a single
two-pipe system with a heating or cooling valve. If you use this system, the device
must know the state (either hot or cold) of the available water. When you use the
hardware water temperature input, the Heat Pump Unit Controller can decide if the
water is sufficiently hot or cold for heating or cooling.

The network inputs nviHotW ater and nviWaterTemp are available for receiving the
water state or temperature, and have priority over the hardware input. If
nviHotWater state and value are zero, the HPU Controller functions as if the water
is cold. If nviHotWater state and value are unequal to zero, the HPU Controller
functions as if the water is hot. If the water temperature is lower than the space
temperature, water is considered cold; if the water temperature is higher than the
space temperature, water is considered hot. The nviHotWater network input has
priority over nviWaterTemp if both values are received.

Preferred SNVT types: SNVT_temp, SNVT_temp_f, SNVT_temp_p.

Window Contact Input

If the Heat Pump Unit Controller is in occupied, bypass, or standby mode, and the
heat pump is in operation (one of the fan speeds is ON), then a switch closure on
the window contact input causes the HPU Controller to enter unoccupied mode.
All outputs turn OFF until a demand from the unoccupied heating and cooling
space temperature setpoints commands the unit into heating or cooling.

Preferred SNVT types: SNVT_lev_disc, SNVT_occupancy, SNVT_switch.

Table 3: Sensor and Switch Preferred SNVT Type (Part 1 of 2)

Sensor or Switch Preferred SNVT Type

Auxiliary Alarm Input SNVT_amp

SNVT_amp_ac
SNVT_amp_f
SNVT_lev_disc

Bypass Contact Input SNVT_lev_disc

SNVT_lev_occupancy

Coil Differential Pressure Input SNVT_press_f SNVT_press_p
Coil Frost Contact Input SNVT_lev_disc SNVT_switch
Discharge Temperature Input SNVT_temp

SNVT_temp_p

Emergency Contact Inp ut SNVT_lev_disc

SNVT_lev_occupancy

Fan Speed Selector Input SNVT_lev_disc

SNVT_lev_occupancy

Fan State Input SNVT_amp

SNVT_amp_ac
SNVT_amp_f

Mode Selector SNVT_hvac_mode

SNVT_lev_percent
SNVT_switch
SNVT_temp_f
SNVT_temp_p

SNVT_switch

SNVT_temp_f

SNVT_switch

SNVT_switch

SNVT_lev_percent
SNVT_switch
SNVT_lev_disc

LX Series Heat Pump Unit Controller User's Guide 25

Table 3: Sensor and Switch Preferred SNVT Type (Part 2 of 2)

Sensor or Switch Preferred SNVT Type

Occupancy Input SNVT_lev_disc

SNVT_lev_occupancy

Outdoor Temperature Input SNVT_temp

SNVT_temp_p

Pump State Input SNVT_amp

SNVT_amp_ac
SNVT_amp_f

Refrigerant Temperature Input SNVT_temp

SNVT_temp_f

Setpoint Offset Input SNVT_temp

SNVT_temp_diff

Space Humidity Input SNVT_lev_percent
Space Temperature Input SNVT_temp

SNVT_temp_f

Water Temperature Input SNVT_temp

SNVT_temp_f

Window Contact Input SNVT_lev_disc

SNVT_switch

SNVT_switch

SNVT_temp_f

SNVT_lev_disc
SNVT_lev_percent
SNVT_switch

SNVT_temp_p

SNVT_temp_f
SNVT_temp_p

SNVT_temp_p

SNVT_temp_p

SNVT_occupancy

LX Series Heat Pump Unit Controller User's Guide26

Outputs

You can configure the Heat Pump Unit Controller analog outputs as analog, digital,
or PWM outputs. If you configure the analog output as a digital output with the
wizard, it supplies 60 mA at 12 VDC. This function is useful when driving relays
external to the board. See Figure 12.

The characteristics of the analog outputs are described in Table 4.

Analog Output Protection

Analog Outputs are protected by an auto-reset fuse with a maximum current
capacity defined by the following two points:

• 100 mA at 68°F (20°C)

• 0 mA at 140°F (60°C)

Table 4: Tri-Mode Analog Output Characteristics

Mode Maximum Current and Voltage Voltage Range

Digital 60 mA at 12 VDC (200 ohm load) 0 – 12 VDC
Analog 50 mA at 10 VDC 0 – 10 VDC (linear)
PWM 50 mA at 10 VDC 0 or 10 VDC

Connect a diode to
the relay terminal.

(Ir = 1A @ Vr=25V)

12Vdc Relay

Max load 200 Ohms

180

DO1 C DO2 C DO3 C DO4 C DO5 C AO1 AO2–

K

Figure 12: Analog Output Driving an External Relay

Digital Outputs

The digital outputs of the Heat Pump Unit Controller use triacs to switch the output
signal. Each digital output is capable of conducting 1 ampere.

Digital outputs work as a switch to control the current (Figure 13). The current
source is separate from the transformers supplying the current for the HPU
Controller.

The HPU Controller uses a half-wave power supply. Any other half-wave power
supply that connects with the controller through the outputs or inputs must be in
phase with the power supply of the controller.

LX Series Heat Pump Unit Controller User's Guide 27

Note: Do not share grounds between a full-wave and a half-wave power supply.

Power Supply

24 VAC

LC

Maximum Curre nt

1A at 24 VAC

DO1

C

DO

C

2

DO3

DO4

C

C

DO5CAO1 AO

2–

Figure 13: Heat Pump Unit Controller Digital Outputs

By using the heat pump configuration wizard, you can reverse any digital output
scale. Normally ON is a 100% output. When the output is reversed, ON is a 0%
output.

You can override any digital output to a previously set value using the HPU
Controller object override command. The override values are set during the
configuration process. The configuration wizard provides a screen for issuing
object commands including the override command. See the Object Manage section
for more information.

LX Series Heat Pump Unit Controller User's Guide28

Staged Outputs

When there are multiple heating or cooling outputs, you can organize the outputs
into stages that turn on sequentially one after the other. In the general sequence,
heating or cooling stages (n) must be open for the period of time specified in the
minimum heating period before heating or cooling stage (n+1) can turn on. For
example, heating stage 1 must be open for the minimum heating period before duct
heating stage 2 turns on. See Figure 14.

Heating
commanded to
100% ON at
this time.

Stage 1

turns ON.

100%

Stage 1 ON Stage 1 ON

Heating

Effort

Time

Minimum

heating

period

Stage 2

turns ON.

Stage 2 ON

Minimum

heating

period

Stage 3

turns ON.

Stage 3 ON
Stage 2 ON
Stage 1 ON

Minimum

heating

period

Figure 14: Staged Outputs

Output Selections

There are 31 possible output selections. Several output selections are dependent
upon other output selections. For example, you can turn off cooling 1 - 4
depending on the setting of the reversing valve.

Fan Speed 1 - 3

Fan Speed outputs provide digital fan speed control. See the Fan Operation
section for more information on fan speed operation.

Heating Outputs 1 - 4

Heating outputs 1 - 4 are staged outputs that turn ON after heating valve outputs
are open 100%.

Cooling Outputs 1 - 4

Cooling outputs 1 - 4 are staged outputs that turn ON after cooling valve outputs
are open 100%.

Reversing Valve

The reversing valve has two states. If the reversing valve is defined and is ON,
cooling outputs 1 - 3 act as heating outputs.

LX Series Heat Pump Unit Controller User's Guide 29

Humidifier and Dehumidifier Outputs

Both digital and analog humidifier and dehumidifier outputs are available. The fan
must be ON to enable the humidifier and dehumidifier outputs.

The Heat Pump Unit Controller uses the assigned outputs to maintain the humidity
at a level defined by the humidity setpoint on the general settings screen. There is a
delay when switching between humidification and dehumidification. You can enter
the time period for the delay on the general settings screen.

The Heat Pump Unit Controller also offers the possibility to dehumidify with the
cooling coil. See the Humidity Control section for more information. Table 5
describes the assigned outputs.

Table 5: Assigned Outputs

Assigned Output Description

Heat Valve ON-OFF Operates digital heating valve.
Cool Valve ON-OFF Operates digital cooling valve.
Heat Cool Valve ON-OFF Operates digital heating-cooling valve according to

Heat Valve Open or Close Operates heating floating valves.
Cooling Valve Op en or Close Operates cooling floating valves.
Heat Cool Valve Open or Close Operates heatin g-cooling floating valves according to

Fan Speed Modulate
(FAN_SPEED_MOD)

Heating Modulate
(HEATING_MOD)

Heating or Cooling Valve Modulate
(HEA TING_VALVE_MOD)
(COOLING_VALVE_MOD)

Pump Provides digital pump control for applications like those

water temperature.

the water temperature.
Provides a variable speed fan control output.

Provides the modulated heating control output.

Provides modulated heating or cooling valve outputs.

involving a geothermal heat pump.

Mode Selection

The Heat Pump Unit Controller has several different modes of operation. Each
mode has a unique group of setpoints. Modes initiate as a result of any of the
following:

• change of value in nviOccCmd

• change of value in nviOccManCmd

• occupied button press

• bypass button press

• window open/close contact
While in any mode, the Heat Pump Unit Controller can enter a heating or cooling

state as required to maintain the space within the limits of the setpoints. Setpoints
for each mode are shown in Table 6.

LX Series Heat Pump Unit Controller User's Guide30

Network Variables Used for Mode Selection

Table 6 shows the values and modes for the nviOccCmd and the nviOccManCmd
network variables.

Table 6: Values of nviOccCmd or nviOccManCmd and Modes

Identifier Heat Pump Unit Controller

Mode

OC_OCCUPIED Occupied mode Occupied heat and cool
OC_UNOCCUPIED Unoccupied mode Unoccupied heat and cool
OC_BYPASS Bypass mode Occupied heat and cool
OC_STANDBY Standby mode Standby heat and cool
OC_NUL Invalid data Unoccupied heat and cool

The network variable nviOccCmd commands the Heat Pump Unit Controller to
change modes according to the value of the variable. You can change the value of
nviOccCmd by a schedule or other supervisory input.

Use the network variable nviOccManCmd to manually command the Heat Pump
Unit Controller to change modes. Possible values of nviOccCmd and
nviOccManCmd are shown in Table 6.

You can manually command the HPU to change modes through network variable
nviOccManCmd. Because manual commands (commands entered by the operator)
have priority over mode commands from a scheduler node, nviOccManCmd has
priority over nviOccCmd. Both network variable inputs have priority over the
occupancy contact or bypass button press. See Table 7.

Setpoints

Table 7: Priorities of Mode Changing Inputs

Priority Level

1 Window Contact Allows unoccupied mode.
2 nviOccManCmd manual mode change
3 nviOccCmd scheduled mode change
4 Occupancy contact enter occupied mode
5 Bypass button press enter bypass mode and start

1. Priority 1 is the highest.

1

Input Function

the bypass timer

If nviOccCmd and nviOccManCmd are set to OC_NUL, OC_BYPASS, or
OC_STANDBY, and the occupancy contact is OFF or unassigned, then the Heat
Pump Unit Controller is in unoccupied mode.

When the window contact is ON, the schedule is set to OC_UNOCCUPIED, and
the fan and all other mechanical equipment cease operation. For example, if the
window is opened, an unoccupied room remains unheated ensuring that heat and
energy is not lost.

If nviOccCmd and nviOccManCmd are set to OC_NUL, OC_BYPASS, or
OC_STANDBY, and the occupancy contact is ON, then the Heat Pump Unit
Controller is in occupied mode.

LX Series Heat Pump Unit Controller User's Guide 31

When you press the bypass button in either unoccupied or standby mode, it causes
the Heat Pump Unit Controller to enter bypass mode.

Occupied Mode

Occupied mode makes the building environment comfortable for occupants.

Starting Occupied Mode

Occupied mode begins as result of one of the following events:

• A command is received on nviOccManCmd or nviOccCmd. You can modify
the network variable nviOccCmd by the building schedule. You can also
manually modify the network variable nviOccManCmd at a computer
connected to the network.

• The occupancy switch is closed when both nviOccCmd and nviOccManCmd
are set to OC_NUL, OC_BYPASS, or OC_STANDY.

Occupied mode uses the occupied setpoints that you set when configuring the
controller wizard. During occupied mode, the Heat Pump Unit Controller uses
outputs to heat or cool the space as required to maintain the temperature within the
limits set by the occupied setpoints.

Ending Occupied Mode

The Heat Pump Unit Controller exits occupied mode when any one of the
following events occurs:

• Another state is commanded through network variable nviOccManCmd. Use
this method for a manual override from a computer.

• Another state is commanded through network variable nviOccCmd. Use this
method with a scheduler node.

• The occupancy contact opens while nviOccCmd and nviOccManCmd are set
to OCC_NUL, OC_BYPASS, or OC_STANDY.

• The window contact is closed, and the occupancy status moves to
OC_UNOCCUPIED.

Unoccupied Mode

The Heat Pump Unit Controller uses Unoccupied mode when the building is
empty. Unoccupied mode allows the space temperature a greater variance than in
occupied mode. However, unoccupied mode keeps the building close enough to
the occupied range of temperature that it can be made ready for occupation on a
regular schedule.

Starting Unoccupied Mode

Unoccupied mode starts as a result of one of the following events:

• The unoccupied state is commanded by nviOccManCmd. Use this method for
a manual override.

LX Series Heat Pump Unit Controller User's Guide32

• A schedule change by a supervisory node sets the network variable

nviOccCmd to OC_UNOCCUPIED. Because nviOccManCmd has priority
over nviOccCmd, nviOccManCmd must be set to OC_NUL for the schedule
change to occur.

• The occupancy contact is open or not assigned, and both nviOccManCmd and

nviOccCmd are set to OC_NUL. Use this method to manually switch between
occupied and unoccupied modes.

• The window contact is opened and the Heat Pump Unit Controller enters the

currently scheduled mode, or the mode currently commanded by the
occupancy contact.

Unoccupied mode cannot begin if the Heat Pump Unit Controller is currently in
bypass mode. Unoccupied mode uses the unoccupied setpoints that you set in the
configuration wizard.

During the unoccupied state, the controller heats or cools the space as required to
maintain the temperature within the limits described by the unoccupied setpoints.
In unoccupied mode, the setpoint offset, either from input or network variable, has
no effect on the effective setpoint.

Ending Unoccupied Mode

Unoccupied mode ends when any one of the following situations occurs:

• Another mode is commanded by nviOccCmd whereas nviOccManCmd is set

to OC-NUL. Use this method to implement a schedule.

• Another mode is commanded by nviOccManCmd. Use this method as a

manual override.

• The bypass button on the space temperature sensor is pressed; this button

short-circuits the sensor.

• The occupied contact is closed, and both nviOccCmd and nviOccManCmd are

invalid.

• The bypass contact input is pressed.

• The window contact is closed and the occupancy status moves to

OC_UNOCCUPIED.

Bypass Mode

Bypass mode uses the occupied setpoints to provide a comfortable environment
when individuals are in a space outside of their usual scheduled time.

Bypass mode is temporary. The duration of bypass mode is a period of time called
bypass time. Bypass time is set on the General Settings configuration screen.

When the HPU Controller enters bypass mode, the bypass time period begins.
Conversely, when the bypass time period ends, the HPU Controller exits bypass
mode.

LX Series Heat Pump Unit Controller User's Guide 33

Starting Bypass Mode

You can command the Heat Pump Unit Controller to enter bypass mode by either
nviOccManCmd or by nviOccCmd. See the Network Variables Used for Mode
Selection section for more information.

The Heat Pump Unit Controller enters bypass mode when any of the following
events occur during unoccupied or standby mode:

• The bypass button on the space temperature sensor is pressed.

• The bypass contact is closed.

The Heat Pump Unit Controller does not enter bypass mode if the bypass time is
set to zero.

Ending Bypass Mode

The Heat Pump Unit Controller exits bypass mode when any of the following
events occur:

• an occupancy contact is closed; the HPU Controller enters occupied mode.

• The window contact is closed; the occupancy status moves to
OC_UNOCCUPIED.

• the bypass timer expires; the HPU Controller enters the currently scheduled
mode, or the mode currently commanded by the occupancy contact.

If bypass mode ends due to the expiration of bypass time and nviOccManCmd is
set to OC_BYPASS, the controller sets nviOccManCmd to OC_NUL. This
scenario returns occupancy control to a scheduler using network input nviOccCmd
or to an occupancy contact. If nviOccManCmd were not set to OC_NUL, it would
have priority over nviOccCmd and the occupancy contact.

Standby Mode

In standby mode, the space temperature is allowed a larger amount of variance
than in occupied mode. However, the space is maintained at a temperature close
enough to the occupied setpoints so that it is made ready for occupancy quickly.
Standby is intended for areas such as meeting rooms that are intermittently
occupied during the normal working day.

Starting Standby Mode

Standby mode setpoints are entered during the HPU Controller configuration. The
HPU Controller enters standby mode as a result of either the following events:

• A scheduler node writes a command to nviOccCmd.

• An operator writes a command to nviOccCmd and/or nviOccManCmd.

You can override any nviOccCmd commands with nviOccManCmd. See Table 7
for more information.

Note: For nviOccCmd to be effective, nviOccManCmd must be set to OC_NUL.

LX Series Heat Pump Unit Controller User's Guide34

Ending Standby Mode

The Heat Pump Unit Controller exits standby mode when any one of the following
events occur:

• The bypass button on the temperature sensor is pressed, or the bypass contact

input is ON; these events initiate bypass mode.

• The occupancy contact is closed; this initiates occupied mode.

• The network variable nviOccManCmd is set to another value by an operator or

program.

• The network variable nviOccManCmd is set to another value while

nviOccManCmd is set to OC_NUL; you can use this method to follow a
schedule.

• The window contact is closed, and the occupancy status is set to

OC_UNOCCUPIED.

Slave Mode

Slave mode commands the HPU Controller to follow the heating or cooling
demand of another heat pump. The controller enters slave mode when nviSlave
(SNVT_hvac_status) is bound to the nvoUnitStatus of another unit.

St ate Selection and Description

The controller enters occupied, unoccupied, standby , and bypass modes depending
on the schedule and other inputs, such as the bypass contact switch. Within each
mode, the controller enters additional states, including heat, cool, night purge, and
morning warm-up.

Supervisory Control and Scheduling

The network variable nviApplicMode coordinates the Heat Pump Unit Controller
with a supervisory control such as a schedule or a Human Machine Interface
(HMI). Network variable nviApplicMode is an SNVT_hvac_mode and must be
bound to another SNVT_hvac_mode output from the HMI, supervisory control, or
air handler.

When this connection is complete, the HMI or supervisory control sets the Heat
Pump Unit Controller to different states through nviApplicMode.

For more information about nviApplicMode, see Table 33.

Calculating the Space Temperature Setpoint

When nviApplicMode is set to HVAC Auto, the space temperature setpoint
determines whether the unit enters a heating or cooling state. In the following
section, space temperature setpoint calculations are addressed before state
descriptions to ensure your understanding of how the state is selected.

LX Series Heat Pump Unit Controller User's Guide 35

When you configure the Heat Pump Unit Controller, you enter three pairs of

(

+

+

(

+

=

setpoints for the four operating states. Because bypass mode uses the same
setpoints as occupied mode, there are only three pairs. These setpoint pairs are
classified as occupied, unoccupied, and standby, and are stored in SCPTSetPnts.
SCPT is an acronym for Standard Configuration Property Type.

Depending on the current mode, the Heat Pump Unit Controller selects a pair of
setpoints as the active setpoints. After the selection, the active setpoints are
modified by the following variables:

• nviSetPoint

• nviSetpointOffset

• Setpoint Input

The Effect of nviSetPoint on the Active Setpoints

You can use the LX-HPUL wizard in FX Workbench to change any setpoints with
the variable nviSetPoint. If nviSetPoint has a valid value and the mode is standby
or occupied, then the two active setpoints are calculated as follows:

Setpoint_ move =−

nviSetPo

occupied cool occupied heat

int

=

+

__

2

)

OffsetSetpoint oveSetpoint_mointsActiveSetppointsActive_Set

The value of Setpoint_move and Setpoint Offset is added to each member of the
active setpoint pair. For the following example, the Setpoint Offset value is
considered to be zero.

Example: If nviSetPoint is equal to 75ºF (23.9ºC) and the two setpoints are 72ºF
(22.2ºC) and 68ºF (20ºC), then:

)

F6872

F75oveSetpoint_m

−°=

°

2

F5oveSetpoint_m °

The two setpoints equal 77ºF (25ºC) and 73ºF (22.8°C).
Note: The network variable nviSetPoint is inactive in unoccupied mode.

The Effect of a Setpoint Offset on the Active Setpoints

The Setpoint offset value is added to the pair of currently active setpoints. For
example, if the setpoints are 72°F (22.2°C) and 68°F (20°C) and the setpoint offset
is 2F° (1.1C°), then the values of the setpoints with the offset are (72+2)°F
(22.2+1.1)°C and (68+2)°F (20+1.1)°C.

The two possible sources of a setpoint offset are the network variable
nviSetpointOffset or a hardware input. The nviSetpointOffset variable allows you
to change the value of the setpoint offset.

LX Series Heat Pump Unit Controller User's Guide36

Hardware inputs are secondary to network variable nviSetpointOffset. For the
hardware input to be active, the value of nviSetpointOffset must be invalid,
occupancy mode cannot be unoccupied. The invalid value for nviSetPointOffset is

621.806°F (327.670°C).

Connect the input to a 10k ohm potentiometer in the

conditioned space.

Humidity Control

The heat pump maintains the humidity level at the humidity setpoint that you enter
on the General Settings screen of the Heat Pump Unit Controller configuration
wizard. The humidity setpoint is stored in UCPThumidityLevelSetpoint. Fan speed
one, two, or three must be ON for humidity control to work.

Perform humidity control using a PID loop. Enter the PID loop parameters on the
PID screen of the Heat Pump Unit Controller configuration wizard. For a
description of PID loop control, see

The Heat Pump Unit Controller maintains the humidity level at the humidity
setpoint in three ways:

• switching ON or OFF the HUMIDIFIER_ON_OFF or

DEHUMIDIFIER_ON_OFF

• modulating the HUMIDIFER_MOD or DEHUMIDIFIER_MOD outputs

The PID Loop section.

and

• controlling any cooling equipment outputs
When you select any cooling output, it unlocks the dehumidifying settings. To

dehumidify with a cooling coil, you must enter a minimum cooling override value,
and the fan speed override value. Take into consideration that dehumidification is
more efficient if the air goes through the cooling coil slowly.

When you switch between humidification and dehumidification, the Heat Pump
Unit Controller delays for a fixed time period of 45 minutes.

Note: The humidification and dehumidification outputs have a minimum ON/

OFF time.

Defrost cycle

Use the defrost cycle to melt the accumulated ice on the HPU Controller’s
evaporator. Defrost cycles are necessary in heating mode when the outside air
temperature is low , and there is a possibility of ice accumulation. Ice accumulation
reduces the efficiency of the Heat Pump Unit Controller by reducing the heat
exchange between the evaporator and the outside air.

The HPU Controller enables the defrost cycle if one of the following conditions is
present:

• The refrigerant temperature is lower than the outside air temperature by a

pre-defined temperature differential setpoint.

• The coil differential pressure is higher than the pre-defined differential

pressure setpoint.

LX Series Heat Pump Unit Controller User's Guide 37

• The heat pump has been in operation for the Heat Pump Run Time Before
Defrost in heating mode, and the refrigerant temperature and/or coil
differential pressure is not available.

The Heat Pump Unit Controller disables the defrost cycle if the cycle has been ON
for the Maximum Defrost Time.

If you configure more than one defrost feature, the Heat Pump Unit Controller
enables the defrost feature according to the priority level listed in Table 8.

Table 8: Priorities of Defrost Cycle

Priority Level Defrost Enabled ON

1 Outdoor and refrigerant differentia l te mp erature
2 Coil differential pressure
3 Coil frost contact closure
4 Run time before defrost

Cooling State

The Heat Pump Unit Controller controls the following cooling types:

• digital cooling

• staged digital cooling

• cooling using heat pump

• floating valve cooling

• modulated valve cooling

The HPU Controller uses mechanical cooling. This type of cooling uses chiller
units and cooling coils to remove heat from a building.

Mechanical Cooling

The Heat Pump Unit Controller turns the mechanical cooling outputs ON when all
the following conditions occur:

• Fan speeds 1, 2, or 3 are ON or fan speed modulation is at the minimum speed.

• All heating outputs have been OFF for at least the amount of time defined by
the Change Over Delay on the Heating Cooling-Configuration screen
UCPTchngeOverDelay.

• nviApplicMode must be set to HVAC_AUTO or HVAC_COOL.

• The space temperature input data must be valid, or the Heat Pump Unit
Controller must be slaved to another unit.

• The outdoor temperature must be greater than the Minimum Outdoor
Temperature entered on the Heating-Cooling Configuration screen.

• There must be a cooling demand. A cooling demand occurs as a result of a
comparison between the space temperature and the active cooling setpoint.

LX Series Heat Pump Unit Controller User's Guide38

• If a floating cooling valve is used, one output must be COOL_VALVE_OPEN

and another output must be COOL_VALVE_CLOSE.

• The water used for cooling operation must be cold for the following output

configurations to work:

• heat_cool_valve_on_off

• heat_cool_valve_close

• heat_cool_valve_open

• heat_cool_valve_mod

The water is considered cold when the water temperature is lower than the room
temperature or the nviHotWater input received value or state is zero.

Note: nviHotWater has priority over the water temperature either from the input

sensor or nviWaterTemp.

Cooling Demand

Cooling demand results from any one of the following:

• the error between the active cooling setpoint and the space temperature

• nviSlave

Cooling Output Sequence

During an increasing cooling demand, the first fan stage turns ON, which enables
all mechanical cooling equipment. After this, fan speed two and three turn ON.
During a decreasing cooling demand, fan and mechanical cooling equipment are
disabled in reverse order. However, fan speed one can remain ON in occupied
mode because of the Always On option. See the

Cooling T erminal Load section for

more information.
If a cooling valve output is configured, cooling outputs 1 - 3 turn ON only after

valve outputs are 100% open.
Cooling outputs 1 - 3 are staged outputs. See the

Staged Outputs section for more

information.

Ending the Cooling State

Cooling outputs shut off when the bias reaches a negligible amount. However,
outputs may not shut off when the space temperature reaches the setpoint if the
PID loop control has accumulated bias during the cooling stage.

Heating State

The Heat Pump Unit Controller controls the following heating types:

• digital heating

• staged digital heating

• heat pump heating

LX Series Heat Pump Unit Controller User's Guide 39

• floating valve heating

• modulated valve heating

The Heat Pump Unit Controller turns ON the heating outputs when the following
conditions are present:

• Fan speeds 1, 2, or 3 are ON, or fan speed modulation is at the minimum speed.

• Options for Permit Valve radiation heating

and/or Permit Local radiation

heating are checked.

Unless you configure another input as a reversing valve, all cooling outputs must
be OFF for the period of time defined as Change Over Delay on the Heating
Cooling Configuration screen.

If you configure another input as a reversing valve, the first stage of cooling turns
on at the same time as the reversing valve. See the

Cooling Outputs Used to Heat

section for more information.

Note: You can use cooling outputs to dehumidify. In this instance, you can enable

both cooling and heating outputs at the same time. The option to disable
dehumidification in heating mode was designed to avoid this situation by
keeping the cooling outputs OFF for dehumidifying in heating mode.

• The network variable nviApplicMode must be set to HVAC_AUTO or
HVAC_HEAT.

• The HPU Controller must be operating with the following conditions present:

• The space temperature is received. This temperature can also be received

through a hardware input or through nviSpaceTemp.

• The HPU is slaved to another unit through nviSlave.

• There is a heating demand (see the

Heating Demand section), or the

discharge temperature is above the minimum during a cooling demand.

• If a floating heating valve is used, one output opens the heating valve and

another output closes the valve.

The water source used for the heating coils must be hot for the following control
outputs to work:

• HEAT_COOL_VALVE_ON_OFF

• HEAT_COOL_VALVE_OPEN

• HEAT_COOL_VALVE_CLOSE

• HEAT_COOL_VALVE_MOD

The water is considered hot when the water temperature is warmer then the room
temperature, or nviHotWater receives a value and state different than zero.

Note: The nviHotWater variable has priority over the water temperature read

either from the input sensor or nviWaterTemp.

LX Series Heat Pump Unit Controller User's Guide40

Heating Demand

A heating demand results from the following:

• the error between the active heating setpoint and space temperature

• nviSlave
If heating demand is taken from nviSlave, the HPU Controller is operating in slave

mode and is receiving the heating demand from another unit.

Heating Output Sequence

Heating outputs 1 - 4 are staged outputs. Heating output 1 is the first heating stage
in the stage sequence. See the

Staged Outputs section for more information.

Heating outputs 1 - 4 and Heating_Mod do not turn ON until all heating valve
outputs are at 100%.

Cooling Outputs Used to Heat

Use cooling outputs 1 - 4 to heat if you configure another output as a reversing
valve. The reversing valve turns ON at the same moment as the first stage of
cooling.

If the cooling outputs are used to heat, heating outputs 1 - 4 and Heating_Mod do
not turn on until the cooling outputs are at 100%.

Ending the Heating State

The heating state ends when there is no demand for heating, and the first heating
stage (if any) has endured for more than the minimum heating period.

If the PID loop control has accumulated bias during the heating stage, heating
outputs may not shut off when the space temperature reaches the setpoint. The
output shuts off when the bias reaches zero.

Night Purge

Night Purge freshens the building air before occupation or cools down a building
before morning occupation. The HPU Controller enters Night Purge if
nviApplicMode is set to HVAC_NIGHT_PURGE. This mode results from a
binding with a supervisory Heating, Ventilating, Air Conditioning (HVAC) device,
an HMI, or a scheduling system.

Night Purge is a scheduled operation that does not use any setpoints. During Night
Purge only the fan restarts. Heating and cooling outputs are OFF.

If frost protection is enabled, the heat turns ON if the temperature in the
conditioned space reaches 42.8°F (6°C). The heat turns OFF again once the space
temperature reaches 46.4°F (8°C).

LX Series Heat Pump Unit Controller User's Guide 41

Morning Warm-up

The Heat Pump Unit Controller enters Morning Warm-up when nviApplicMode
has the value of HVAC_MRNG_WRMUP. The HVAC_MRNG_WRMUP value
may be the result of binding nviApplicMode with a network variable from a
supervisory network system, such as nvoTerminalLoad.

Morning Warm-up uses occupied setpoints, and ends when nviApplicMode
commands another state.

Fan Operation

Three fan speeds are available in the Heat Pump Unit Controller. Fan speeds are
started according to heating or cooling demand, and according to the outputs
configured in the Heat Pump Unit Controller configuration wizard. Normal
operation sequence begins with the HPU Controller commanding the first fan
speed to turn ON. After this, the controller starts or modulates all cooling and
heating outputs to their maximum capacity according to their respective demands.
Finally, all other fan speeds are started according to their respective demands.

If the fan option Always On in occupied mode is selected, and the occupancy
status is OC_OCCUPIED or OC_BYPASS, the first fan speed is ON. Otherwise,
the first fan speed starts according to a cooling or heating demand.

Fan speeds two and three are controlled with a cooling and heating demand.
However, heating outputs and cooling outputs must be configured for those fan
speeds to start.

Use fan speeds two and three to increase cool or hot air volume in the room. For
example, during a heating demand, it is not acceptable to increase the air volume if
the discharge air is not reheated; this situation creates discomfort for room
occupants as they receive colder air.

LX Series Heat Pump Unit Controller User's Guide42

The minimum time that any fan speed must be ON before it turns OFF, and the
minimum time that any fan speed must be OFF before it turns ON, are both set in
the Fan-Valve screen of the Heat Pump Unit Controller configuration wizard.
Enter a value in the ON/OFF period box on that screen. See Figure 15.

Figure 15: Fan-Valve Screen of the Heat Pump Unit Controller

Configuration Wizard

Terminal Load

Terminal load describes the energy consumption of a HPU Controller for both
heating and cooling operations. The network variable nvoTerminalLoad transmits
the terminal load of a HPU Controller over the network.

LX Series Heat Pump Unit Controller User's Guide 43

Heating Terminal Load

Negative terminal load values represent heating terminal loads. Heating effort
increases as terminal load decreases. At 100% heating effort, the Terminal Load is

-100% (Figure 16).

Heating Terminal Load

Terminal Load

0%-50%-100%

Time

0%

50%

100%

Heating
Effort

Figure 16: Heating Terminal Load

LX Series Heat Pump Unit Controller User's Guide44

Cooling Terminal Load

Positive terminal load values represent the cooling terminal loads. Terminal load
increases as cooling effort increases. At 100% cooling effort, the Terminal Load is
100% (Figure 17).

Cooling Terminal Load

Terminal Load

100%

50%0%

100%

50%

Time

0%

Figure 17: Cooling Terminal Load

Cooling
Effort

LX Series Heat Pump Unit Controller User's Guide 45

Networking Operations

This section describes the operations that occur only as a result of network
connections. Properties of network variables are also addressed.

Slave Operation

The HPU Controller follows the demands of another heat pump unit controller if
nviSlave is bound to the nvoUnitStatus of the other controller.

The network variable nviSlave is type SNVT_hvac_status.

Load Shedding

If the Heat Pump Unit Controller receives an input on nviShedding, it reduces its
output. As the value of nviShedding increases, the Heat Pump Unit Controller
further reduces its output.

For example, if nviShedding is at 25%, heating and cooling outputs do not exceed
75%. Shedding stops if the frost protection is enabled, and the space temperature
falls under 46°F (8°C).

The network variable nviShedding is a type SNVT_switch.

Setting up Network Connections

The Heat Pump Unit Controller interfaces through the Local Operating Network
(LON) to controllers using the LonTalk® protocol.

Whereas the Heat Pump Unit Controller can function without a network
connection, the network variables sent and received over the LON by the Heat
Pump Unit Controller can affect all of its operations.

LX Series Heat Pump Unit Controller User's Guide46

Network Outputs

The network variables have the attributes Heartbeat, Send on Delta, and Throttle in
common. These attributes are defined in Table 9. Table 10 defines the associated
network inputs.

Table 9: Network Outputs

Attribute Description

Heartbeat Heartbeat is the maximum amount of time that must pass before the network

Send on Delta Send on Delta causes a message to be sent when the monitored data

Throttle Throttle sets the minimum update period and acts as a limit on excessive

variable automatically transmits. The presence of the heartbeat attribute
indicates that functions are proceeding normally. Failure to receive a signal at
the other node within a heartbeat interval causes an alarm message to be
sent over the network.

Heartbeat is like a countdown timer. Every time that a message is sent, the
Heartbeat timer resets to the full heartbeat value.

Heartbeat signals are not always sent. If the monitored data changes more
than is required by the Send on Delta setting within a shorter period of time
than the heartbeat, the data is sent on the network, and the heartbeat
message is not sent. Instead, the heartbeat timer is reset and counts down
again.

The heartbeat timer is reset every time that a message is transmitted. Only
when the heartbeat timer reaches zero is the heartbeat message sent.

Heartbeat provides a method of ensuring that points have not lost connection,
and that the network is functioning. Whereas throttle restricts how often
messages are sent, heartbeat ensures that messages are sent regularly.
Heartbeat is disabled by setting it to zero.

changes by a previously set proportion. Send on Delta restricts extraneous
network noise by transmitting only signals that indicate a meaningful amount
of change.
If the monitored data does not change for a period of time equal to the
heartbeat interval, the data is sent as a heartbeat signal.

network traffic. If the value of a point on the network is constantly fluctuating
at a rapid rate and set to Send on Delta, the network can be flooded by data
from that point. Throttle prevents the variable from transmitting more than
once every minimum update period regardless of how many fluctuations have
occurred during that period. For example, rapid motion of the damper could
drastically increase network traffic. Damper oscillations could also cause
network traffic problems if data were sent on every cycle of oscillation.
Throttle can prevent network congestion in either of these cases by limiting
the number of sends per time interval to a meaningful number. The larger the
throttle number, the less frequently the network variable transmitted. Throttle
units are in seconds. Throttle is disabled by setting it to zero.

Table 10: Network Inputs

Attribute Description

Heartbeat The maximum time period that the network variable waits for a message

before entering the heartbeat failure state determines the heartbeat effect on
a network input. When a heartbeat failure state is entered, the value becomes
invalid, and an alarm is sent.

Persistent When the network variable is marked as Persistent, the value is written to

Electrically Erasable Programmable Read-Only Memory (EEPROM). Once
written to EEPROM, the network variable value is preserved through power
outages and resets. Every time a new network variable value is received, the
new value is written into EEPROM.

Because EEPROM can only accept a limited number of data writes, be
careful how you use the persistent attribute. See the Persistent Network
Variables section for more information.

LX Series Heat Pump Unit Controller User's Guide 47

Optimum Start

Optimum Start prepares the space for occupancy in advance of the occupied
period. If you start heating or cooling at the optimum time before the occupied
period begins, the HPU Controller creates a comfortable space that is ready for
occupancy without wasting energy. You can enable Optimum Start on the Options
screen of the Heat Pump Unit Controller configuration wizard. Select the boxes
labeled Enable Optimum Start for heating and Enable Optimum Start for cooling.

The HPU Controller maintains statistics that compare the outside temperature to
the time required for the space to reach the occupied setpoints. These statistics are
used to calculate the length of time required for Optimum Start.

Because the Optimum Start time is calculated every day for the current outside air
temperature, it is much more energy efficient than simply starting the occupancy
period before the actual arrival of occupants.

To configure Optimum Start, enter a value in the Maximum start time box to limit
the Optimum Start time period. Optimum Start begins no sooner than the
Maximum start time before the occupancy change. For example, if the space enters
the occupied mode at 8:00 A.M. and the Maximum start time is 30 minutes, then
Optimum Start does not begin before 7:30 A.M. Of course, Optimum Start can still
begin at any time that is less than 30 minutes before 8:00 A.M.; for example,
7:41 A.M.

When statistics are not available, there are two options: The first option starts
heating or cooling when the space occupancy changes. The second option allows
Optimum Start to use the Maximum start time. To enable this feature, select the
box labeled Use maximum time if no statistics on the Options configuration
screen.

Regardless of which setting you choose, the first samples are saved when the HPU
Controller does not have any statistics; these samples include the outside air
temperature and the time required to reach the setpoint. Each day, Optimum Start
uses the time recorded from the previous day’s sample. For example, if the Heat
Pump Unit Controller recorded that the space reached the occupied setpoint in
25 minutes the first day, then on the second day the HPU Controller would begin
Optimum Start 25 minutes before occupancy. If a maximum start time has been
entered, the HPU Controller may use a value derived from the samples that is less
than the maximum start time. However, the Heat Pump Unit Controller does not
use a start time that is greater than the maximum start time value.

On the third day, the HPU Controller has two samples stored, and uses the two
samples to calculate the Optimum Start time given the current outdoor
temperature. From this point, all Optimum Starts are statistically calculated by the
HPU Controller using its saved samples.

Requirements for Optimum Start

Requirements for Optimum Start are as follows:

• The next state and time to the mode must be defined in advance.

LX Series Heat Pump Unit Controller User's Guide48

• There must be a scheduler and the schedule must be properly bound to the Heat

Pump Unit Controller using nviOccCmd.

• The network variable nviOccCmd must be set to SNVT type

SNVT_tod_event. This is performed using the Changeable Nv Manager view
of the LX-HPUL device in FX Workbench.

Since the Optimum Start is based on statistics resulting from the room temperature
and the outside air temperature, you must configure the outdoor temperature as an
input or receive it from the network through nviOutdoorTemp.

Emergency Operation

Emergency Operation is for situations where the ventilation system should be shut
down (for example, to combat the spread of a fire).

Emergency Operation stops any fans, pumps and heating or cooling action.

Emergency Initiation

Setting nviEmergCmd to EMERG_SHUTDOWN and closing the emergency
contact wired to the emergency input initiates emergency modes.

The network variable nviEmergCmd has priority over the emergency contact. The
network variable nviEmergCmd is an SNVT_hvac_emerg (103). The invalid value
is EMERG_NUL.

Normal Operation

When there is no emergency, and operations are normal, nviEmergCmd is set to
EMERG_NORMAL.

The PID Loop

PID loops provide precise control over space temperature and ventilation.
The control loop modulates its output to drive its input to a setpoint. Control loop

inputs are the sensor readings of the temperature. Examples of these control loops
include the fan speeds and the heating or cooling outputs.

LX Series Heat Pump Unit Controller User's Guide 49

The difference between the input and the setpoint is called the error. Controller
output is a function of the error.

SpaceSensor Output

Input

Controller

Setpoint

Output

Figure 18: PID Controller with Input, Setpoint, and Output

The Heat Pump Unit Controller provides PID control settings through its
configuration wizard. The PID screen is shown in Figure 19.

Figure 19: Heat Pump Unit Controller Configuration Wizard: PID Screen

LX Series Heat Pump Unit Controller User's Guide50

For space temperature, discharge temperature, and humidity levels, there are
settings for proportional, integral, and derivative gain. Each of these gains
contributes to the final output as shown in Figure 20.

Proportional

Figure 20: Total Output Composed of P, I, and D Components

++ =

Integral

Derivative

Tota l O u tp ut

Proportional

Proportional control provides an output that is proportional to the error. The error
is multiplied by a number called the gain. The result is used to produce the output.

For example, if the room temperature is 69°F (20.6°C) and the setpoint is 72°F
(22.2°), then the error is 3F° (1.7C°). If the gain is equal to 10% per F°, the output
is 30% of the maximum output value.

Integral

The integral component has a gain and time setting. These work together to
remove errors that accumulate over time.

Gain

The integral gain is similar to the proportional gain. The error is multiplied by the
value you entered as integral gain. If the gain is equal to 5% per °F and the error is
2F°, the integral output is 10% of the maximum possible output signal.

Time

The integral gain differs from the proportional gain because the output increases
the longer that the error persists. This increase occurs because the product of the
error multiplied by the integral gain is periodically added to the output. When you
enter the time, you are entering the length of the time period over which the error is
added.

LX Series Heat Pump Unit Controller User's Guide 51

How It Is Used

Imagine a building in a cold climate where the temperature of a certain space is
never quite warm enough. A log of the temperature of this space would produce a
graph such as Figure 21.

Heat is OFF.

Setpoint

Heat is ON

Temperature

8:00 8:30 9:0010:00

Time

Space Temperature

Figure 21: Never Quite Warm Enough:

Using Only a P Controller

In Figure 21, the temperature never quite falls low enough to turn on the
proportional heat.

However, with a Proportional Integral controller, the error would accumulate over
time. Periodically, a portion of the error would be added back into the error. The
error would accumulate and would finally be large enough to turn the heat ON. See
Figure 22.

Space

Heat is OFF.

Setpoint

Temperature

Heat is ON

Temperature

8:00 8:30 9:0010:00

Time

Heat is ON.

Error accumulates.

Figure 22: Heating Using a PI Controller

Derivative

Derivative control opposes sudden changes in the input value.
Whereas Integral control is able to correct errors that persist over time, derivative

control can respond quickly to sudden changes.

LX Series Heat Pump Unit Controller User's Guide52

A derivative of a function is the rate of change of the function. Therefore, in a
graph of temperature versus time, the derivative is the rate of change of the
temperature. In this case, rate of change means the change in temperature per unit
time. For example, this rate could be degrees per minute.

As mentioned previously, derivative control opposes the rate of change. As an
example scenario, consider a hospital lobby in the arctic. Because the lobby
changes temperature often, it has its own local heaters that are controlled by a PID
loop. Every time the hospital doors open, the temperature in the lobby decreases
quickly . This sudden drop in temperature is a large rate of change. The lar ge rate of
change is opposed by the derivative control. The derivative control increases the
output of the PID loop that increases the output of the heaters. As the lobby
temperature comes closer to the setpoint, the derivative control output decreases
and finally becomes zero when the lobby temperature reaches setpoint.

Derivative control usually responds to measured values rather than to the actual
direct input. By doing so, the derivative control is prevented from creating large,
short spikes in the controller output. These spikes are the derivative control’s
response to a sudden increase or decrease in error due to setpoint changes.

Gain

The derivative gain is the amplification of the derivative output. This gain is
measured as a percentage per unit of change, where units are degrees Centigrade or
Fahrenheit. If a value of 50 is entered into the Gain box, then each unit of error
causes a 50% increase in derivative control output.

Time

Time refers to the period between measurements of the input. If the time is set to
3 seconds, and the gain is 25%/F°, then the derivative output is 25% of the error
for each degree of error and recalculates every 3 seconds.

LX Series Heat Pump Unit Controller User's Guide 53

Dead Band

The dead band is a range of input values surrounding the central setpoint. This
range of values is close enough to the setpoint that their effect is unnoticeable.
While the input lies within the dead band, deviations from the setpoint are not

1

/

calculated as errors. For example, if the dead band is equal to
then the dead band extends from setpoint - 1/

1

/

amount of deviation allowed is ±

Deadband with Value of x

Deadband Limits

x. See Figure 23.

2

As long as input stays within the deadband, the error
will be zero. As long as the error is zero, the PID loop
will not change its output signal.

x to setpoint +

2

x to the setpoint,

2

1

/

x. The maximum

2

e
d
u

t

i
n
g
a

M

Deadband Limits

0.5x

x

0.5x

Setpoint

Time

Input

As soon as the input exceeds the
deadband, the PID loop will sense
an error at its input. Whatever the
PID outputs will do next, depends
on the PID loop settings.

Figure 23: Effect of Dead Band upon PID Loop Error

Using dead bands reduces mechanical wear and tear on moving parts because the
mechanical parts no longer oscillate to accommodate trivial errors.

Alarm Operation

The Alarms Configuration screen (shown in Figure 24) of the Heat Pump Unit
Controller configuration wizard provides a number of user-set alarms. You can
configure and enable the alarms to match the requirements of your current site.
User-set alarms are available for the following control points:

• space air temperature

• discharge air temperature

• space humidity

• auxiliary alarm

• fan alarm

• pump alarm

LX Series Heat Pump Unit Controller User's Guide54

In addition to the preceding user-set alarms, other alarms are provided. These
include:

• heart beat alarms for network inputs

• disconnect alarms for sensor points

• an emergency mode alarm

Figure 24: Alarms Configuration Screen

LX Series Heat Pump Unit Controller User's Guide 55

Alarm Features

Alarms have a number of features that enable you to automatically and carefully
monitor critical system information. Many of these features are visible in
Figure 25. Table 11 describes the Alarm Features.

Features of a Deviation Alarm

Space Temp C°

Offset = 2C°
Alarm Delay = 10 minutes

10.0 min

Monitored
Variable

25

Setpoint

22
20

15

Time

Monitored variable exceeds value of offset + setpoint
at this time.

An alarm message is not sent as the monitored
variable is in the alarm state for less time than the
value of the alarm delay.

2.0 C°

2.0 C°

10.0 min

Monitored variable
enters alarm state
at this time.

Alarm message is
sent here after the
expiration of the
alarm delay.

Upper
limit of
Offset

Lower
limit of
Offset

Figure 25: Space Temperature Alarm

Table 11: Alarm Features (Part 1 of 2)

Feature Description

Monitored Variable Displays the network variable or control point that is monitored by the

alarm. For example, if you have an alarm that sends a message
whenever a space temperature deviates too far from the setpoint, then
the monitored variable is the space temperature.

Alarm State Enables when a monitored variable has a value that causes an alarm.
Alarm Offset Displays the amount that the monitored variable can deviate from the

setpoint before entering the alarm state. See Figure 25. An offset
causes the alarm to become active when the value of the monitored
variable is greater than or less than the range of values equal to the
setpoint ± the offset. Alarms that use an alarm offset are often called

deviation alarms.

Alarm Delay Displays the period of time that the monitored variable must be in the

alarm state before an alarm message is generated. See Figure 25 and
Figure 26.

LX Series Heat Pump Unit Controller User's Guide56

Table 11: Alarm Features (Part 2 of 2)

Feature Description

Alarm Low Limit Displays a value that is less than the setpoint. When the monitored

Alarm High Limit Displays a value that is greater than the setpoint. When the monitored

variable becomes equal to or less than the alarm low limit, an alarm
message transmits over the network. Alarms that use a low limit are
often called low limit alarms. See Figure 26.

variable becomes equal to or more than the alarm high limit, an alarm
message transmits over the network. Alarms using high limits are often
called high limit alarms. See Figure 26.

A number of alarms respond to the timing of network variables. Some of these are
called heartbeat alarms since they respond to the heartbeat value. The heartbeat is
the maximum length of time that can occur between transmissions of a variable on
the network. If this time is exceeded, an alarm sounds.

Use the network variables nvoHPalarm and nvoUnitStatus to transmit alarms.

Alarm Types

Four alarm types are used in the Heat Pump Unit Controller. Table 12 describes
these alarm types.

Table 12: Alarm Types

Alarm Type Description

Digital Alarms Monitors the state of digital network variables or hardware inputs. Digital

High Limit Alarms Reports when an analog network variable or hardware input is greater

Low Limit Alarms Reports when an analog network variable or hardware input is less than

Deviation Alarms Reports when a monitored analog value deviates from its setpoint by

alarms also indicate when digital network variables differ in state. For
example, the fan output and the fan state should always be the same. If
they differ, a digital alarm transmits a message on the network.

than a user-set value called a high limit.

a user-set value called a low limit.

more than a user-set value known as an alarm offset.

Alarm Procedure

When an alarm condition occurs, the following changes take place:

• The appropriate bits of nvoStatus and nvoHPalarm are set.

• The in_alarm field of nvoUnitStatus is set to one.

• The network variable nvoUnitStatus transmits information about the heat

pump object.

The following text sorts the alarms by type, describes the conditions that generate
an alarm, and organizes associated bits of the nvoStatus and nvoHPalarm into a
table. Alarm types are heartbeat alarms, disconnect alarms, status alarms, and
user-set alarms.

Heartbeat Alarms

Heartbeat Alarm time values are set on the Network Input pages of the Heat Pump
Unit Controller configuration wizard or by modifying SCPTmaxRcvTime.

LX Series Heat Pump Unit Controller User's Guide 57

Features of an Alarm Using High and Low Limits

Lower Alarm Limit = 18°C

Supply Temp C°

Upper Alarm Limit = 24°C
Alarm Delay = 10 minutes

10.0 min

Upper
Alarm
Limit

Lower
Alarm
Limit

25

22

Setpoint

20

18

15

Time

Monitored variable falls below lower limit.
An alarm message is not sent as the monitored

variable is in the alarm state for less time than the
value of the alarm delay.

Monitored
Variable

Monitored variable
enters alarm state
at this time.

10.0 min

Alarm message is sent at
this time after the expiration
of the alarm delay.

Figure 26: Discharge Temperature Alarm

The Bit # refers to the Bit Number of nvoHPalarm. The column programmatic
name refers to the programmatic name of nvoHPalarm with the format type
UNVT_rt_alarm that relays the status of the object. If a heartbeat alarm is ON, a
communication failure alarm sounds. The Bit #13 of nvoStatus, programmatic
name comm._failure, turns ON. Table 13 describes the Heartbeat Alarms.

Table 13: Heartbeat Alarms

Monitored Point Monitored

Variable

Application Mode
Coil Differential

Pressure
Discharge Temperature
Fan State
Fan Speed Command
Hardware Output Value
Occupancy Command
Outdoor T emperature
Pump State
Refrigerant

Temperature
Setpoint Offset
Shedding Command

LX Series Heat Pump Unit Controller User's Guide58

nviApplicMode SCPTmaxRcvTime 1 nviApplicModeHeartBeat
nviCoilDiffPress SCPTmaxRcvTime 13 nviC o ilDiffPressHeartBeat

nviDischarge Tem p SCPTmaxRcvTime 6 nviDischargeTempHeartBeat
nviFanState SCPTmaxRcvT ime 7 nviFanStateHeartBeat
nviFanSpeedCmd SCPTmaxRcvTime 14 nviFanS peedCmdHeartBeat
nviExtCmdOutput(x) SCPTmaxRcvTime 16–22 nviExtCmdOutputxHeartBeat
nviOccCmd SCPTmaxRcvTime 3 nviOccCmdHeartBeat
nviOutdoorTem p SCPTmaxRcvTime 10 nviOutdoorTempHeartBeat
nviPumpState SCPTmaxRcvTime 15 nviPumpStateHeartBeat
nviRefrigerantTemp SCPTmaxRcvTime 12 nviRefrigTempHeartBeat

nviSetPtOffset SCPTmaxRcvTime 2 nviSetPtOffsetHeartBeat
nviShedding SCPTmaxRcvTime 8 nviSheddingHeartBeat

Delay Time Bit # P rogrammatic Name

Table 13: Heartbeat Alarms

Monitored Point Monitored

Variable

Slave Input
Space Humidity
Space Temperature
Water Temperature
Water Temperature

State (hot/cold)

nviSlave SCPTmaxRcvTime 9 nviSlaveHeartBeat
nviSpaceRH SCPTmaxRcvTime 11 nviS p aceRHH eartBeat
nviSpaceTemp SCPTmaxRcvTime 0 nviSpaceT em pHeartBeat
nviWaterTemp SCPTmaxRcvTime 4 nviWaterTem pHeartBeat
nviHotWater SCPTmaxRcvTime 5 nviHotWaterHeartBeat

Delay Time Bit # Programmatic Name

Disconnect Alarms

The column heading Bit # refers to the Bit Number of nvoHPalarm. The column
programmatic name refers to the programmatic name of nvoHPalarm with the
format type UNVT_rt_alarm that relays the status of the object. If a heartbeat
alarm is ON, an electrical fault alarm sounds. The Bit #11 of nvoStatus,
programmatic name electrical_fault, turns ON. Table 14 describes the Disconnect
Alarms.

Table 14: Disconnect Alarms

Sensor Time

Disconnected

Space Temperature
Sensor

Discharge Air
Temperature Sensor

Outdoor Air
Temperature Sensor

Refrigerant
Temperature Sensor

Water Temperature
Sensor

Setpoint Offset 30 seconds 37 SetpointOffsetElecFault

30 seconds 32 SpaceTempSensorFault

30 seconds 33 DischargeTempSensorFault

30 seconds 34 OutdoorTempSensor

30 seconds 35 RefrigerantTempSensor

30 seconds 36 WaterTempSensorFault

Bit # Programmatic Name

Emergency Mode Alarms

Emergency Mode is described in the Emergency Operation section. Emergency
Mode alarm begins when the emergency mode begins. The column programmatic
name refers to the programmatic name of nvoHPalarm with the format type
UNVT_rt_alarm that relays the status of the object.

Table 15: Emergency Mode Alarm

Monitored State Bit # Programmatic name

Emergency Mode 48 Emergency

User-Set Alarms

The Bit # refers to the Bit Number of nvoHPalarm. The column programmatic
name refers to the programmatic name of nvoHPalarm with the format type
UNVT_rt_alarm that relays the status of the object. If a user-set alarm comes ON,
an out-of-limits alarm sounds. The Bit #4 of nvoStatus, programmatic name
out_of_limits, turns ON.

LX Series Heat Pump Unit Controller User's Guide 59

These settings can be entered on the Alarm screen of the Heat Pump Unit
Controller configuration wizard. See Figure 24.

Table 16: Configuration Variables for User-Set Alarms

Monitored
Point

Space
Temperature

Discharge
Air
Temperature

Space
Humidity

Fan State

Pump State

Auxiliary
Alarm Input

Alarm
Type

Setpoints Bit#Programmatic

Name

Location
Setpoints/
Delta

Deviation active heating

Low low limit setpoint 40 LowDischargeTemp UCPTsupplyTemp

High high limit

Deviation setpoint - offset 42 LowSpaceRH UCPThumidityAla

Digital Fan input differs

Digital Fan input differs

Low lower than low

High higher than high

setpoint - offset
active cooling

setpoint + offset

setpoint

setpoint + offset 43 HighSpaceRH

from state of fan
output

from state of fan
output

limit setpoint

limit setpoint

38 LowSpaceTemp UCPTspaceTemp

39 HighSpaceTemp

41 HighDischargeTemp UCPTsupplyTemp

44 FanStateMismatch UCPTFanCurrent

45 PumpStateOff N/A UCPTpumpAlarm

46 AuxiliaryLowAlarm UCPTauxiliaryAlar

47 AuxiliaryHighAlarm UCPTauxiliaryAlar

Alarm
Delta Field

AlarmLoLimit
Field

AlarmHiLimit Field

rm Delta Field

Threshold

mLoLimit field

mHiLimit field

Time Delay
Location

UCPTspaceTemp
Alarm Time Field

UCPTsupplyTemp
Alarm Time Field

UCPThumidityAlar
m Time Field

UCPTfanAlarm
Time

Time

UCPTauxiliaryAlar
mtime field

Setting up the Heat Pump Controller

This section provides you with step-by-step instructions on how to set up the Heat
Pump Unit Controller using the configuration wizard. This section includes
definitions of the terms used in the configuration wizard and a short explanation of
how to use each section of the wizard.

Each screen of the configuration wizard is introduced by a large graphic of that
screen and discussed under its own heading. For example,

Configuration

.

Persistent Network Variables

When a network variable is marked as persistent, the network variable value is
written to Electrically Erasable Programmable Read-Only Memory (EEPROM).
Every time it receives a new network variable value, the new value is written into
EEPROM. Once written to EEPROM, the network variable value is preserved
through power outages and resets.

However, EEPROM only accepts a limited number of data writes. The number of
writes that EEPROM accepts is large, but it is still limited. Therefore, if the
network variable input is constantly changing, it could exhaust the ability of the
EEPROM to store it in permanent memory.

Heating-Cooling

However, if the value of the network variable is constant, and if it is received on
the network input at a fixed time interval, this does not cause the EEPROM to
write new data. The EEPROM only writes new data when the data value changes.

LX Series Heat Pump Unit Controller User's Guide60

For these reasons, network variables that change infrequently (such as
nviSetPoint) are better candidates for persistence than others.

Setting Units

Measurement units are shown at the bottom of the Heat Pump Unit Controller
configuration wizard menu. Select the measurement units before you perform any
other tasks. When you change the measurement units, all unsaved information you
have entered into the HPU Controller configuration wizard is lost.

If you are using Imperial units of measure (such as degrees Fahrenheit, inches of
water, or Btu) please see the

Units in LONWORKS Networks section.

Note: If you change your measurement system, all the SNVT format types also

change. The measurement unit you select in the wizard, either SI or
Imperial, affects the nvoHwInputx SNVT format type. Once you configure
an input through the wizard and select an SNVT Type, the format type is
written in the database and a change of the measurement system unit no
longer affects that network variable.

Input Configuration

When you configure inputs you set the signal type, signal interpretation, and the
SNVT that transmits the information over the network.

Inputs are configured from the sensor configuration wizard. Launch the wizard
from either the Heat Pump Unit Controller configuration wizard or the Hardware
Input L

ONmARK object in the LX-HPUL Wizard view of the device.

Figure 27: Inputs Configuration Window

LX Series Heat Pump Unit Controller User's Guide 61

To configure an input:

1. The numbers in the Sensor Input column correspond to the input numbers of
the LX-HPUL. Click the drop-down arrow next to the input number you wish
to configure.

2. Select an input type. Table 17 gives a brief description of the possible
selections.

Table 17: Sensor Input Usage Options

Input Selection Description

UNUSED Input not used by Heat Pump
SPACE_TEMP Space temperature input
DISCHARGE_TEMP Discharge air temperature input
OUTDOOR_TEMP Outdoor air temperature input
REFRIGERANT_TEMP Refrigerant temp erature input
WATER_TEMP Water temperature input
SETPOINT Setpoint input
SPACE_HUMIDITY Space humidity input
COIL_DIFF_PRESSURE Coil differential pressure input
AUXILIARY_ALARM Auxiliary alarm input
FAN_STATE Fan state input
FAN_SPEED_SELECT OR Fan speed selector input
MODE_SELECTOR HVAC mode selector input
PUMP_STATE Pump state input
OCC_CONTACT Occupancy contact input
BYPASS_CONTACT Bypass contact input
WINDOW_CONTACT Window contact input
COIL_FROST_CONTACT Coil frost contact input
EMERGENCY_CONTACT Emergency contact input

LX Series Heat Pump Unit Controller User's Guide62

3. Click Configure. The Sensor Configuration dialog box appears.



Figure 28: Sensor Configuration Dialog Box

4. Enter the configuration settings and click OK.
The sensor configuration properties determine the frequency of network variable

propagation. Use the Delta Value and Throttle to adjust a node’s overall
transmission rate to the available network bandwidth. The transmission rate is
particularly important when the network variable value changes frequently (for
example, a sensor reading).

Heartbeat (Max Send Time)

The maximum time period between automatic transmissions of the network
variable on the network (whether the value of the variable has changed or not). Set
Heartbeat to 0 to disable the Heartbeat.

Heartbeat is also referred to as Maximum Send Time.

Throttle (Min Send Time)

Throttle is the minimum time period that must pass between network variable
updates on the network. If the value of the network variable changes by more than
the configured Delta Value, an update is sent only after this time expires. Set
Throttle to 0 to disable Throttle.

Throttle is also referred to as Minimum Send Time.

LX Series Heat Pump Unit Controller User's Guide 63

Delta Value

Indicates the minimum value change required to update the associated network
output variable.

Override Value

The value the network variable adopts when the Sensor object is in the overridden
state.

Default Value

The value the network variable adopts when the Sensor object is in the disabled
state, or the sensor reading is invalid.

Sensor Hardware Properties

The hardware configuration properties of a particular sensor input. Settings made
here correspond to the characteristics of the sensor hardware connected to the
input.

Input Signal Interpretation

Determines how the input reading is converted into units of measurement (for
example, degrees Celsius). See Table 18. Signal Interpretation Type selections
might be limited if a Heating, Ventilating, and Air Conditioning (HVAC) object
(for example, a heat pump object) uses a particular sensor input implemented on
the same node.

Table 18: Input Signal Interpretation Types

Input Signal Interpretation
Type

DISCONNECTED Input not used by Heat Pump
LINEAR Linear Interpolation
TRANS_TABLE Translation Table
DIGITAL 2-state input (ON/OFF)
MULTI-LEVEL Multi-level input uses signal increment
STD_THERMISTOR Predefined translation table
SETPOINT_OFFSET Linear Interpolation with deadb and

Description

The configuration property entry fields change depending on the selected Signal
Interpretation Type.

Signal Type

Determines the input signal type of the connected sensor. The following signal
types are supported:

RESISTANCE - Resistive of Contact input
VOLTAGE_0_10V - 0 to 10 Volt input
MILLIAMPS_4_20MA - 4 to 20 milliamp input

LX Series Heat Pump Unit Controller User's Guide64

Thermistor Type

If the associated input is a thermistor (THR) type, use this field to select the
predefined translation table for linear interpolation of input values.

Table 19: Thermistor Types

Thermistor Type Description

DEFAULT_TYPE ACI/10 K-CP
TYPE_2 ACI/10 K-CP
TYPE_3 ACI/10 K-AN
TYPE_7 Greystone 10 K, Type 7
TYPE_12 Mamac Systems 10K, Type 12
TYPE_24 Greystone 10K, Type 24

Offset

The sensor-specific zero offset in measurement units. This value is added after
translation/conversion of the raw signal.

Max Value, Min Value

Depending on the Input Signal Interpretation type, this settings has a different
meaning. For LINEAR and SETPOINT_OFFSET types, they determine the range
of the sensor in measurement units mapped to the predefined span of the hardware
input signal (10 V, 16 mA, and so on). Linear interpolation calculates the sensor
value.

For all other non-discrete Input Signal Interpretation Types, these settings define
the upper and lower limit of the sensor object's output value.

Reverse

Use this check box to reverse the object's output value. This setting applies to
discrete inputs (ON/OFF) only.

Increment

Defines the increase of input signal necessary to increment the output value (for
example, network variable) by one, starting from zero.

For example: If the increment setting is 2 V, the network variable value is 3 at 6 V.

TransTable

Opens a small window providing a table of 16 signal/value pairs to define a
translation table for conversion of raw measured data into units of measurement.
Input values are in kilo-ohm, V, or mA, with respect to the Input Signal Type
chosen. Output values are in units according to the object’s selected output
network variable type. Only values within the sensor range defined by Max Value
and Min Value are considered.

LX Series Heat Pump Unit Controller User's Guide 65

Get Value

This button is active when the associated device is configured, online, and
connected. Once all hardware properties are set appropriately, click this button to
retrieve the current sensor value form the network.

Configuring an Input Represented as a LONMARK Object

To configure an input represented as a LONMARK object:

1. Select the Hardware Input L
Wizard view.

2. Select the Sensor Configuration wizard on the right side of the view.

3. Click the Launch button.

4. Click the Configure button.

5. In the Sensor Configuration dialog box, make the required selections.

ONMARK object on the left side of the LX-HPUL

Output Configuration

When you configure outputs you define the function, output override value and
output signal type.

Configure outputs through the Hardware Output wizard and launch them from the
HPU Controller configuration wizard Object Outputs Configuration screen
(Figure 29).

LX Series Heat Pump Unit Controller User's Guide66

T able 20 describes all possible outputs that you can select from the Object Outputs
Configuration screen.

Figure 29: Object Outputs Configuration Screen

Launch the Output wizard from either the Heat Pump Unit Controller
configuration wizard.

Use the Hardware output to control any equipment that is not related to the Heat
Pump Unit Controller. To do so, configure the output with the Actuator wizard
launched from the object outputs configuration. In the Johnson Controls® Heat
Pump Configuration wizard, leave the corresponding output UNASSIGNED. To
control that output, use the nviExtCmdOutputx.

Table 20: Output Selection and Description (Part 1 of 2)

Selection Output Description

FAN_SPEED_1 Fan control output, speed 1
FAN_SPEED_2 Fan control output, speed 2
FAN_SPEED_3 Fan control output, speed 3
LOCAL_HEATING_1 Heating control output, stage 1
LOCAL_HEATING_2 Heating control output, stage 2
LOCAL_HEATING_3 Heating control output, stage 3
LOCAL_HEATING_4 Heating control output, stage 4
LOCAL_COOLING_1 Cooling and heat pump heating control output, stage 1
LOCAL_COOLING_2 Cooling and heat pump heating control output, stage 2
LOCAL_COOLING_3 Cooling and heat pump heating control output, stage 3
LOCAL_COOLING_4 Cooling and heat pump heating control output, stage 4

LX Series Heat Pump Unit Controller User's Guide 67

Table 20: Output Selection and Description (Part 2 of 2)

Selection Output Description

REVERSING_VALVE Two-state (opened or closed) reversing valve output
HUMIDIFIER_ON_OFF Humidifier control output
DEHUMIDIFIER_ON_OFF Dehumidifier control output
PUMP Pump control output
HEAT_VALVE_OPEN Heating floating valve output, open command
HEAT_VALVE_CLOSE Heating floating valve output, close command
COOL_VALVE_OPEN Cooling floating valve output, open command
COOL_VALVE_CLOSE Cooling floating valve output, close command
HEA T_COOL_VALVE_OPEN Heating/cooling floating valve output, open command
HEA T_COOL_VALVE_CLOSE Heating/cooling floating valve output, close command
FAN_SPEED_MOD Fan control output, variable speed
HEATING_MOD Modulated heating control output
HEATING_VALVE_MOD Modulated heating valve output
COOLING_VALVE_MOD Modulated cooling valve output
HEA T_COOL_VALVE_MOD Modul ated heating/cooling valve output
HUMIDIFIER_MOD Modul ated humidifier control output
DEHUMIDIFIER_MOD Modulated dehumidifier control output

Output Signal Types

Available output types depend on which output signals you select. Three output
types are available:

Digital: A signal which has only two discrete states–ON or OFF

•

•P

WM: A pulsed signal, where the time duration of the pulse (called the duty

cycle) varies proportionally to the value transmitted. For example, a large duty
cycle is translated as a larger value.

•

Analog: A signal that is continuous over its entire range from 0 to 10 volts.

Configuring an Output

To select and configure an output:

1. On the Output screen, numbers in the column Control Output correspond to the
output numbers. Click the drop-down arrow next to the control output number
that you want to configure.

2. Select an output type. See Table 20 for a brief definition of the possible
selections.

3. If you want to assign an override value, select the Permit Override check box
and then enter an override value as a percentage of the total output value. If
you have chosen a digital output such as FAN_ON_OFF, then the override box
changes to provide you with the option of ON or OFF for your override.

LX Series Heat Pump Unit Controller User's Guide68

Note: Outputs are overridden by use of the Heat Pump Unit Controller LONMARK

Object command. This command is available from the Object Manage
screen of the Heat Pump Unit Controller configuration wizard.

4. Click Override ON to enable the override and Override OFF to disable it.

5. Select the Use Local Hardware check box if the output is connected to a

physical actuator such as a motor, dehumidifier, or damper.

6. Click Configure.



Figure 30: Hardware Output1

7. In the Output T ype box, click the drop-down arrow and select the output signal

appropriate for your application. The output signal selection presented to you
is dependent upon the choice you made in Step 2. See the

Output Signal Types

section for more information.

Note: Reverse Output - Normally, an output is ON when the output components

are supplying 100% of the rated voltage. If you want the output to supply
0% of the rated voltage when ON, select the Reverse check box. For a
digital output, the output is normally ON when the contacts are closed.
When you reverse a digital output, the output is ON when the contacts are

open.
You have now configured an output.
The architecture of the Heat Pump Unit Controller configuration wizard allows

you to place functional blocks for your outputs on your network graphic. This
ability increases the amount of network information that appears on the diagram
and makes it easier to connect and display network variables.

LX Series Heat Pump Unit Controller User's Guide 69

Creating a Functional Block

To create a functional block:

1. Place a Heat Pump Unit Controller device on the network diagram.

2. In the network diagram, select the Heat Pump Unit Controller device. Click
and drag a functional block from the template onto the FX Workbench
diagram. The Functional Block wizard opens.

3. Verify that the Heat Pump Unit Controller appears in the box labeled Device.

4. Select an output type.

5. Click OK.

6. Name the functional block.

7. Click OK.

You have now created and placed a functional block.

Configuring an Output Represented as a Functional Block

To configure an output represented as a functional block:

1. Select the Hardware Output in the LX-HPUL view in FX Workbench. Click
the Launch button. The Actuator configuration wizard opens (Figure 31).

Figure 31: Hardware Output Configuration

LX Series Heat Pump Unit Controller User's Guide70

2. In the Output Type box, select the type of output signal. See the Output Signal

Types section for more information.

Note: Reverse Output - Normally , an output is ON when the output components

are supplying 100% of the rated current and voltage. For a digital output,
the ON state occurs when the contacts are closed. If you want the output
when ON to supply 0% of the rated current and voltage or for the digital
contacts to be open, then select the Reverse check box.

3. Assign an override value by entering an override value as a percentage of the

total output.

Note: Normally, digital outputs are closed at 100% and open at 0%. See

preceding
actuator L

Reverse Output text. Outputs are overridden by use of the

ONMARK Object command. This command is available from the

Object screen of the actuator wizard.

4. Enter a default value in the Default Value box.
The default values are used when the Heat Pump Unit Controller is in the default

state. The HPU Controller may enter the default state at startup. The state that the
HPU Controller enters at startup is selected during commissioning.

Heating-Cooling Configuration

On the heating-cooling configuration screen (Figure 32), you define the following:

• occupied, standby, and unoccupied setpoints in both heating and cooling mode

• maximum and minimum discharge temperatures

• the change over delay (See A in Figure 32)

• mechanical cooling minimum operating times (See B in Figure 32)

Figure 32: Heating-Cooling Configuration Screen

LX Series Heat Pump Unit Controller User's Guide 71

Table 21: Heating-Cooling Configuration Parameters

Field Description

Heating
Occupied/Bypass
Standby
Unoccupied
Maximum Discharge

Temperature
Minimum Heating

Time

Turn ON Heat
Stage 1 before using
Modulated Heating

Cooling
Occupied/Bypass
Standby
Unoccupied
Minimum Discharge

Temperature
Minimum Time ON
Minimum Time OFF
Mechanical
Minimum Time ON
Minimum Time OFF
Minimum Outdoor

Temperature

Heat/Cool Change Over
Delay

Displays the heating setpoint for the occupied and bypass states.
Displays the heating setpoint for the standby state.
Displays the heating setpoint for the unoccupied state.
Displays the highest discharge air temperature you allow during the

heating state.
Displays the length of time that the duct and perimeter heating must stay

ON once it has turned ON, and the length of time that the heating must
stay OFF once it has turned OFF. Minimum heating time affects duct
heating, perimeter heating, and staged out put s. Once a st ag ed outp ut has
changed state, the next staged output cannot change state until the
minimum heating time has passed.

Note:

Minimum Heating Time does not apply to modulated heating.

Use this option when you have a gas-heating system that needs to have its
contact energized before modulating the gas-heating valve.

Displays the cooling setpoint for the occupied and bypass states.
Displays the cooling setpoint for the standby state.
Displays the cooling setpoint for the unoccupied state.
Displays the minimum temperature of the discharge air that you allow

during the cooling state.
Displays the minimum ON time for both heating and mechanical cooling.
Displays the minimum OFF time for mechanical heating and cooling.

Displays the minimum ON time for both heating and mechanical cooling.
Displays the minimum OFF time for mechanical heating and cooling.
Displays the minimum outdoor air temperature at which mechanical

cooling is allowed. Mechanical cooling disables when the outdoor air
temperature is less than this value.

Displays the time interval that must pass before heating can occur after
cooling or cooling can occur after heating.

LX Series Heat Pump Unit Controller User's Guide72

Fan-Valve Configuration

On this screen, you select the type of fan input, fan operation, and floating valve
operating properties (Figure 33). See Table 22 for Fan-Valve Configuration
Parameters.

Figure 33: Fan-Valve Configuration Screen

Table 22: Fan-Valve Configuration Parameters (Part 1 of 2)

Field Description

Fan
Fan Speed Allows your sensor to measure the fan speed.
Fan Current Allows your sensor to measure the current drawn by the fan.
Current Threshold Sets the current at which you consider the fan to be ON. This

affects the alarm that compares the states of the fan input and
fan output.

Minimum Speed D i s pla ys th e fa n mi ni mu m sp ee d .
ON/OFF Period Displays the period of time that must pass before th e fa n ca n

Always ON in Occupied Mode Forces the fan to run continuously during occupied mode. If

Digital Valves
Minimum ON/OFF Period Displays the period of time that must pass before the fan can

turn ON after turning OFF; or the fan can turn OFF after turning
ON.

this box is not checked, the fan runs only when there is a
heating or cooling demand.

turn ON after turning OFF, or the fan can turn OFF after turning
ON.

LX Series Heat Pump Unit Controller User's Guide 73

Table 22: Fan-Valve Configuration Parameters (Part 2 of 2)

Field Description

Valves
Minimum Position Displays the valves minimum position when there is a heating

Drive Time for Floating
Valves

or cooling demand. The valves are fully closed when there is
no heating or cooling demand.

Displays the period of time required for the valve to move from
the fully closed to the fully open position.

PID Configuration

The Heat Pump Unit Controller uses PID Loops to control the space temperature,
discharge temperature, and humidity (Figure 34).

Figure 34: The PID Configuration Screen

LX Series Heat Pump Unit Controller User's Guide74

Table 23 applies to the space temperature, discharge temperature, and humidity
loops.

Table 23: PID Configuration Parameters

Field Description

Proportional Gain Displays the gain per unit of the error.
Integral Gain Displays the gain per unit of the error.
Integral Time Displays the error repetitively sampled, and the integral gain is added to

the output. The period of time between samples is the integral time. Enter
the integral time for your process.

Derivative Gain Displays the gain per unit of the error.
Derivative Time Displays the derivative time–the time between two samples of the error.

Dead Band Displays a number to define the size of the dead band. The dead band is

Use Discharge Air
Temperature Only
for Limitation

The two samples are compared to find the change in the error.

a range of values symmetrical about the setpoint. See the Dead Band
section for more information.

Allows the Heat Pump Unit Controller to control the unit with the room
demand, and limits the discharge temperature between the minimum and
maximum discharge temperature.

If this option is unchecked, the Heat Pump Unit Controller tries to maintain
the calculated discharge temperature setpoint. The discharge setpoint is
calculated with a linear equation between the minimum and maximum
discharge air temperature and the space PID loops.

Alarm Configuration

Using this window, you can set the alarm high limits, low limits, offset, and alarm
delays (Figure 35). See Table 24 for Alarm Configuration Parameters.

Figure 35: Alarm Configuration Screen

LX Series Heat Pump Unit Controller User's Guide 75

Alarms monitor network variables or control points. These variables or points are
called
alarm message to be transmitted, then the monitored variable is in the

Table 24: Alarm Configuration Parameters

monitored variables. When a monitored variable has a value that causes an

alarm state.

Field Description

Alarm Delay Displays the length of time that an input must be in the alarm state before an

alarm sounds.

Alarm Offset Displays the amount of deviation from the setpoint that causes an alarm to

sound.

Alarm Low
Limit

Alarm High
Limit

Displays a value less than when the alarm becomes active. The alarm becomes
active when the monitored variable falls below this value.

Displays a value greater than which the alarm becomes active. The alarm
becomes active when the monitored variable rises above this value.

Space Temperatures and Humidity

The Space Temperature and Humidity alarms have an alarm delay and an alarm
offset only. For the alarm to become active, the monitored temperature must be
outside of the range bounded by the setpoint plus ± alarm offset. However, this
condition must exist for a length of time greater than the alarm delay to activate the
alarm.

Discharge Temperature and Auxiliary Alarm

Both the Discharge Temperature and Auxiliary alarms have an alarm delay, high,
and low limit. In this case, the alarm becomes active when the monitored input is
outside of the range marked by the high and low limits. This condition must occur
for a length of time greater than the alarm delay to activate the alarm.

Fan Alarm

The Fan Alarm applies to the fan state only. The fan alarm becomes active when
one of following conditions exists for a time period greater than the alarm delay:

• The fan command is ON, and the fan input differs from the fan output, or the
fan current is lower than the fan current threshold, or

• The fan command is OFF, and the fan input differs from the fan output, or the
fan current is higher than the fan current threshold.

Whether a digital fan is ON or OFF, a decision is made by monitoring the fan
speed or fan current. The alarm delay must be long enough to allow the fan to
reach the ON or OFF stage. The fan speed or fan current level is set in the
Fan-Valve Configuration screen.

Similarly, a variable speed fan requires time to speed up or slow down so that its
speed matches the output. The alarm delay must be long enough to allow the fan to
reach its commanded speed; otherwise, false alarms are generated.

LX Series Heat Pump Unit Controller User's Guide76

Pump Alarm

The Pump alarm only applies to the pump state. The pump alarm is activated when
the pump input differs from the pump output for a time period longer than the
alarm delay.

General Settings Configuration

Figure 36 shows the General Settings Configuration screen.

Figure 36: General Settings Configuration Screen

LX Series Heat Pump Unit Controller User's Guide 77

Radiation Heating

Radiation heating provides the option of starting heating outputs without starting
the heat pump fan. Hot air mixes with the air in the space by natural convection.
When you are not using the heating outputs, the option text appears in gray.
Table 25 describes Radiation Heating.

Table 25: Radiation Heat Parameters

Field Description

Permit Valve
Radiation Heating

Permit Local
Radiation Heating

Heat Order During
Unoccupied Mode

If selected, this enables the valve heating outputs to start on a heating
demand before the fan starts.
If this option is cleared, the valve heating outputs remain OFF if the fan is
not ON.

If selected, this enables the local heating outputs to start on a heating
demand before the fan starts. If this option is cleared, the local heating
outputs remain OFF if the fan is not ON.

This enables you to select your unoccupied heating order: Radiation First,
Ventilation Only.
If you select Radiation First, the valve and/or heating outputs start first on
a heating demand. If the option Ventilation Only is selected, the fan must
be ON to start any heating outputs.

Options Configuration

On the Options Configuration screen (Figure 37) you configure the following:

• Optimum Start

• Humidity Control

•Defrost Cycle

LX Series Heat Pump Unit Controller User's Guide78

• Frost Protection

Figure 37: Options Configuration Screen

Optimum Start

Optimum Start prepares the space for occupancy in advance of the occupied
period. The HPU Controller uses stored daily statistics to calculate the length of
time required each day to reach the occupied setpoints just as actual occupancy
begins.

Optimum Start is described in the

Note: For Optimum Start to work, the network variable nviOccCmd must be set

to SNVT type SNVT_tod_event. This procedure is done on the Network
Inputs screen. See

Change Type in Table 29 entitled Network Input

Parameters for more information.

Optimum Start section.

LX Series Heat Pump Unit Controller User's Guide 79

Table 26: Options Configuration

Field Description

Maximum Start Time Sets the maximum length of time before the start of occupancy

Enable Optimum Start for
Heating

Enable Optimum Start for
Cooling

Use Maximum Start Time if
No Statistics

mode so that the Heat Pump Unit Controller can start to heat or
cool the space.

Allows the Heat Pump Unit Controller to heat the space so that
the space temperature is within the occupied setpoints when the
occupied period begins.

Allows the Heat Pump Unit Controller to cool the space so that
the space temperature is within the occupied setpoints when the
occupied period begins.

Allows the Heat Pump Unit Controller to use the maximum start
time as the length of time needed to heat or cool the space
before occupancy. Once Optimum Start statistics have been
recorded, the HPU Controller uses Optimum Start time periods
calculated from the statistics. The Maximum Start Time is only
used to limit the length of the Optimum Start Time.

Bit 58 of the UCPTobject Options when set enables this option.
If this box is not selected, the Heat Pump Unit Controller begins
to heat or cool the space at the beginning of the occupied period.

After the first start, it heats or cools the space at the recorded
Optimum Start time. After the second start, it heats or cools the
space at the calculated Optimum Start time.

Frost Protection

Select the Frost Protection box to have the heat turned ON at a space temperature
of 43°F (6°C) and turned off at 46°F (8°C). The heat turns ON independently of
the temperature control. For example, the heat turns ON when nviApplicMode is
set to HVAC_OFF.

The heat turns ON in the order determined by the heating order.

Defrost Cycle

Defrost cycle is necessary to remove the accumulated ice on the evaporator of the
Heat Pump Unit Controller. Table 27 describes defrost cycle fields.

Table 27: Defrost Cycle

Field Description

Start On Refrigerant/Outdoor
Differential Te mperature

Start On Coil Differential
Pressure

Heat Pump Run Time Before
Defrost

Maximum Defrost Time Displays the maximum time that defrost cycle can be ON.

Displays a differential temperature that enables the defrost
cycle.
To use this option, you must have both refrigerant and outdoor
air temperature configured as inputs or have them received
through a network variable.

Displays a coil differential pressure that enables the defrost
cycle.

Displays a value for the heat pump run time before defrost.
Use this option in heating mode and only if the coil differential
pressure is not available, or the refrigerant and the outdoor air
temperature are not available.

LX Series Heat Pump Unit Controller User's Guide80

Humidity Control

You can control Humidity many ways in the Heat Pump Unit Controller; with a
cooling coil, a humidifier or a dehumidifier. Table 28 describes the Humidity
Control.

Table 28: Humidity Control

Field Description

Setpoint Displays the space humidity setpoint as a percentage.
Humidifier/Dehumidifier

Minimum ON/OFF Time

Enable Dehumidifying Cycle Enables the dehumidifier using the cooling coil.
Disable in Heating Mode Disables the dehumidifier using the cooling coil in heating

Cooling Override Valu e Displays the minimum value for the cooling internal control

Fan Speed Override Value Displays the value for the fan speed in dehumidification mode.

Displays the period of time that must pass before the humidifier
or dehumidifier can turn ON after turning OFF , or turn OFF after
turning ON.

Note: Humidifier/Dehumidifier ON/OFF time does not apply to

modulated humidifier and dehumidifier outputs.

mode.

loop. In dehumidification process, this is the smallest value for
the cooling outputs. For example, if you have one modulating
cooling valve and the value for the cooling override is 55%, the
valve always opens at 55% or more in dehumidification mode.

If you have 3 fan speeds, and you want speed 2 to be open,
enter the value 66.66%, which corresponds to 2 fan speeds on
a 3 fan speed possibility (2/3).

LX Series Heat Pump Unit Controller User's Guide 81

Network Input Configuration

Figure 38 shows the Network Input Configuration dialog box. Table 29 describes
the parameters.

Figure 38: Network Input Configuration Screen

Table 29: Network Input Parameters

Field Description

Heartbeat Sets the maximum time between updates for the associated network input.

Persistent Allows the network variable to remain in memory after a power failure and/or

When the heartbeat interval has passed without an update, the network input
enters the heartbeat failure state and its value becomes invalid.

reset. Do not make frequently changing network variables persistent. See
the Persistent Network Variables

section for more information.

Heartbeat Alarms

An alarm occurs if the period between received values of these variables exceeds
the value you enter into the Heartbeat column. For more information, see the

Alarm Operation section.

Network Output Configuration

The Network Outputs screen enables you to control network traffic to reduce
network congestion. Data is transmitted as quickly as is necessary for your
application (Figure 39).

The Network Outputs screen enables you to control the frequency of network
variable transmissions through several different parameters. On the Network
Outputs Configuration screen you configure the following:

LX Series Heat Pump Unit Controller User's Guide82

• Heartbeat period for network outputs

• Send on Delta quantity

• Throttle settings for several network outputs
You can also set the maximum send time and minimum send time for all other

network variables. Table 30 describes the parameters.

Figure 39: Network Output Configuration Screen

Table 30: Network Output Configuration Parameters

Field Description

Heartbeat The maximum time period between transmissions of the network

variable.

Send on Delta Enter the amount of change of the value of the network variable that

Throttle Enter the minimum time period that must pass before a network variable

Other NVO The values entered in the Other NVO box affect all other network

must occur before the variable is transmitted. The network variable is
transmitted whenever this much change occurs.

is transmitted.

variable outputs that do not have individual values.
Heartbeat: Enter the maximum time between transmissions of network
variables.
Throttle: Enter the minimum time between transmissions of network
variables.

LX Series Heat Pump Unit Controller User's Guide 83

Object Manage

The Object Manage screen enables you to view the status of the LONMARK object
and use L
HPU Controller configured, and be in communication with the FX supervisory
controller (Figure 40). Table 31 describes the Object Manage parameters.

ONMARK commands. To use this screen, you must be online, have the

Figure 40: Object Manage

Table 31: Object Manage Parameters (Part 1 of 2)

Field Description

Device State Displays the current state of the LONMARK object.
Object Status Displays the object status information from nvoUnitStatus. Messages

Get Status Allows you to update status information in the object status list.
Clears Status Clears all status flags, removing all messages. Clicking Get Status

Override ON Places the Heat Pump Unit Controller into the override state. Control

Override OFF Ends the Override state.

such as Communications Failure or Electrical Fault appear here. A red
icon indicates an active state and a gray icon indicates an inactive
state.
When the box Display Active Only is selected, only the red active
status flags appear. The Object Status area is blank when the Heat
Pump Unit Controller is in its normal state. For a description of each of
the Object status pane messages, see the Object Status

retrieves new information. This can be used to check if a problem
condition is solved.

outputs including the network variables and linked hardware outputs
are set to their configured override value or state.

section.

LX Series Heat Pump Unit Controller User's Guide84

Table 31: Object Manage Parameters (Part 2 of 2)

Field Description

Enable Enables the controller after an override.
Disable Sets the L

control outputs are at their configured disabled state.

Request Allows advanced users to query L

and commands.
To query the L
list beside the request button. Click the Request button. Requests are
handled by SNVT_obj_request. See Table 32 for values of
SNVT_obj_request.

ONMARK object to the disabled mode. In the disabled mode,

ONMARK using the LONMARK object

ONMARK object, select a command from the drop-down

Table 32: Values for SNVT_obj_request

1

Value Identifier Meaning

0 RQ_NORMAL Enable object and remove override
1 RQ_DISABLED Disable object
2 RQ_UPDATE_STATUS Report object status
3 RQ_SELF_TEST Perform object self test
4 RQ_UPDATE_ALARM Update alarm status
5 RQ_REPORT_MASK Repo rt status bit mask
6 RQ_OVERRIDE Override object
7 RQ_ENABLE Enable object
8 RQ_RMV_OVERRIDE Remove object override
9 RQ_CLEAR_STATUS Clear object status
10 RQ_CLEAR_ALARM Clear object alarm
11 RQ_ALARM_NOTIFY_ENABLED Enable alarm notification
12 RQ_ALARM_NOTIFY_DISABLED Disable alarm notification
13 RQ_MANUAL_CTRL Enable object for manual control
14 RQ_REMOTE_CTRL Enable object for remote control
15 RQ_PROGRAM Enable programming of special configuration

16 RQ_CLEAR_RESET Clear the RESET_COMPLETE flag.
17 RQ_RESET Execute a reset sequence, set the

properties

RESET_COMPLETE flag when done.

1. Not all commands are available in the Heat Pump Unit Controller.

Object Status

The Object Status messages are listed here with references to tables describing the
causes.

Communication Failure

This message results from a heartbeat failure on a network variable input that sets
the comm_failure bit of nvoStatus. See Table 13.

LX Series Heat Pump Unit Controller User's Guide 85

Electrical Fault

This message indicates that a local hardware sensor is disconnected. The
disconnect condition sets the electrical_fault bit of nvoStatus. See Table 14 for a
list of the possible disconnected sensors.

Out of Limits

This message indicates that a monitored point has exceeded limits set by the
person who configured the device. The out-of-limits sets the out_of_limits bit of
nvoStatus. See Table 16.

Disabled

Active if the device has been disabled by pressing the Disable button.

In Alarm

Active if a communications failure or electrical fault has occurred or if any of the
conditions in the Alarm Configuration window have been met.

In Override

Active if the device has been placed into override by pressing the Override button.

Out of Service

Active when the LX-HPUL cannot control the temperature in the zone of the
control because it is not receiving a space temperature or there is no slave input
(nviSlave).

Network Variables

The following text describes all network variables found in the Heat Pump Unit
Controller.

nviApplicMode

Use this network variable input to coordinate the Heat Pump Unit Controller with
the following:

• an air handler controller

• any other supervisory controller

• a human interface device

See Table 33 for nviApplicMode values.

LX Series Heat Pump Unit Controller User's Guide86

Type: SNVT_hvac_mode (108)

Table 33: nviApplicMode

Value Identifier Notes

0 HVAC_AUTO Controller automatically changes between application

1 HVAC_HEAT Heating only
2 HVAC_MRNG_WRMUP Application-specific morning warm up
3 HVAC_COOL Cooling only
4 HVAC_NIGHT_PURGE Application-specific night purge
5 HVAC_PRE_COOL

6 HVAC_OFF Controller not controlling outputs
7 HVAC_TEST

8 HVAC_EMERG_HEAT
9 HVAC_FAN_ONLY Air not conditioned, fan turned on

10 HVAC_FREE_COOL
11 HVAC_ICE
0xFF HVAC_NUL Value not available

1. Not supported in the Heat Pump Unit Controller.

modes

Application-specific pre-cool

Equipment being tested
Emergency heat mode

Cooling with compressor not running
Ice-making mode

1

1

1

1

1

nviCoilDiffPress

Transmits coil differential pressure from a network device to the Heat Pump Unit
Controller. Network values has priority over local sensor values.

Type: SNVT_press_p (113)

LX Series Heat Pump Unit Controller User's Guide 87

nviDischargeTemp

Transmits discharge temperature from a network device to the Heat Pump Unit
Controller. Network values have priority over local sensor values.

Type: SNVT_temp_p (105)

nviEmergCmd

Use this network variable input to command the Heat Pump Unit Controller into
different emergency modes. It is typically set by a supervisory node. See Table 34.

Type: SNVT_hvac_emerg (103)

Table 34: nviEmergCmd

Value Identifier Actions

0 EMERG_NORMAL Normal operation
1

2 EMERG_DEPRESSURIZE The damper moves to the fully closed position
3

4 EMERG_SHUTDOWN Fan, heating, and cooling are turned OFF
5

0xFF EMERG_NUL Value not available

EMERG_PRESSURIZE

EMERG_PURGE

EMERG_FIRE

1

1

1

The damper moves to the fully open position

The damper moves to the fully open position
Fan, heating, and cooling are turned OFF

---

1. Not supported in the Heat Pump Unit Controller.

nviExtCmdOutputx

These network variable inputs receive the output signal (state and percentage) to
control any output that is unassigned and configured through the controller
configuration wizard. They are listed following the output number
(nvoExtCmdOutput1, nvoExtCmdOutput2,...).

Type: SNVT_switch (95)

nviFanSpeedCmd

This network variable input receives the fan speed demand. It receives a value
between 0-100% and a state of 0-1. For example, for three fan speeds: fan speed 1
starts when nviFanSpeedCmd is over 33.33%, fan speed 2 starts when
nviFanSpeedCmd is over 66.66%, and fan speed 3 starts when nviFanSpeedCmd
equals 100.00%. To start, the field of the nviFanSpeedCmd must be ON, state 1.

Type: SNVT_switch (95)

nviFanState

This network variable input receives the fan state. When state and value are not set
to zero, the fan state is considered ON. When state or value is set to zero, the fan
state is considered OFF.

Type: SNVT_switch (95)

LX Series Heat Pump Unit Controller User's Guide88

nviHotWater

This network variable input receives the water state. Water state refers to whether
the water is hot or cold.

When state and value are not set to zero, the water state is hot. When state or value
is set to zero, the water state is cold.

Type: SNVT_switch (95)

nviOccCmd & nviOccManCmd

Use these network variable inputs to command the Heat Pump Unit Controller
object into different occupancy modes.

Type: SNVT_occupancy (109); SNVT_tod_event (128)

Table 35: Values of nviOccCmd and Modes

Value Identifier Heat Pump Unit Controller Mode

0 OC_OCCUPIED Occupied Mode
1 OC_UNOCCUPIED Un occupied mode
2 OC_BYPASS Bypass mode
3 OC_STANDBY Standby mode
0xFF OC_NUL Invalid data

The network variable nviOccCmd commands the Heat Pump Unit Controller to
change modes according to the value of the variable. The value of nviOccCmd
itself can be changed by a network schedule or a manual change.

While in any mode, the Heat Pump Unit Controller can enter a heating or cooling
state as required to maintain the space within the limits of the setpoints.

nviOutdoorTemp

This network variable input receives the outdoor air temperature.

nviPumpState

This network variable input receives the pump state.
When state and value are not set to zero, the pump state is considered ON. When

state or value is set to zero, the pump state is considered OFF.
Type: SNVT_switch (95)

nviRefrigTemp

This network variable input transmits refrigerant temperature from a network
device to the Heat Pump Unit Controller. Network values have priority over local
sensor values.

Type: SNVT_temp_p (105)

LX Series Heat Pump Unit Controller User's Guide 89

nviSetPoint

This network variable input changes the temperature setpoints for the occupied and
standby modes via the network. The individual heating and cooling setpoints for
the occupied and standby modes are calculated from nviSetPoint. See

nviSetPoint on the Active Setpoints section for more information.

Type: SNVT_temp_p (105)

The Effect of

nviSetPtOffset

This network variable input shifts the temperature setpoint by adding the value of
nviSetpointOffset to the current setpoint. This network variable operates only on
occupied and standby setpoints and does not affect the unoccupied setpoint. See

The Effect of nviSetPoint on the Active Setpoints section for more information.

Type: SNVT_temp_p (105)

nviShedding

This network variable input reduces the Heat Pump Unit Controller power
consumption. For example, if nviShedding is set to 25%, then heating and cooling
do not exceed 75%.

Type: SNVT_lev_percent (81)

nviSlave

This network variable input forces the Heat Pump Unit Controller to follow the
demands of another Heat Pump Unit Controller. It is typically bound to the
nvoUnitStatus of the other Heat Pump Unit Controller.

Type: SNVT_hvac_status (112)

nviSpaceRH

This network variable input transmits space humidity from a network device to the
Heat Pump Unit Controller. Network values have priority over local sensor values.

Type: SNVT_temp_p (105)

nviSpaceTemp

This network variable input transmits space temperature from a network device to
the Heat Pump Unit Controller. Network values have priority over local sensor
values.

Type: SNVT_temp_p (105)

LX Series Heat Pump Unit Controller User's Guide90

nviWaterTemp

This network variable input transmits water temperature from a network device to
the Heat Pump Unit Controller. Network values have priority over local sensor
values. If both nviHotWater and nviWaterTemp are received from the network,
nviHotWater has priority over nviWaterTemp.

Type: SNVT_temp_p (105)

nvoCtrlOutput

These network variable inputs send the output signal, whether state or percentage,
to any actuators.

They are listed following the output number (nvoCtrlOutput1,
nvoCtrlOutput2, …).

Type: SNVT_switch (95)

nvoDischargeSetPt

This network variable output sends the discharge setpoint in use by the heat pump
object.

Type: SNVT_temp_p (105)

nvoEffectSetPt

This network variable output sends the effective setpoint in use by the heat pump
object.

Type: SNVT_temp_p (105)

nvoFanSpeed

This network variable output sends the fan speed.
Type: SNVT_switch (95)

nvoHPalarm

Table 36 organizes the associated programmatic names and Bit numbers for
nvoHPalarm. For more information about this network variable, see the

Procedure section.

Type: SNVT_state_64 (165)

Alarm

LX Series Heat Pump Unit Controller User's Guide 91

Format: UNVT_hp_alarms

Table 36: nvoHPalarm (Part 1 of 2)

Programmatic Name Bit

Number

nviSpaceTempHeartBeat 0 Heartbeat failure reported from nviSpaceTemp
nviApplicModeHeartBeat 1 Heartbeat failure has occurred in nviAp plicMode
nviSetPtOffsetHeartBeat 2 Heartbeat failure has occurred in nviSetPtOffset
nviOccCmdHeartBeat 3 Heartbeat failure has occurred in nviOccCmd
nviWaterTempHeartBeat 4 Heartbeat failure has occurred in nviWaterTemp
nviHotWaterHeartBeat 5 Heartbeat failure has occurred in nviHotWater This

nviDischargeTempHeartBeat 6 Heartbeat fa ilure has occurred in nviDischAirTemp
nviFanStateHeartBeat 7 Heartbeat failure has occurred in

nviSheddingHeartBeat 8 Heartbeat failure has occurred in nviSh edding
nviSlaveHeartBeat 9 Heartbeat failure has occurred in nviSl ave
nviOutdoorTempHeartBeat 10 Heartbeat failure has occurred in nviOutdoorTemp
nviSpaceRHHeartBeat 11 Heartbeat failure has occurred in nviSpaceRH
nviRefrigTempHeartBeat 12 Heartbeat failure has occurred in nviRefrigTemp
nviCoilDiffPress 13 Heartbeat failure has occurred in nviCoilDiffPress
nviFanSpeedCmdHeartBeat 14 Heartbeat failure has occurred in

nviPumpStateHeartBeat 15 H eartbeat failure has occurred in nviPumpState
nviExtCmdOutputxHeartBeat 16-21 Heartbeat failure has occurred in

SpaceTempSensorFault 32 Space temperature sensor is disconnected for

DischargeTempSensorFault 33 Discharge temperature sensor is disconnected for

OutdoorTempSensorFault 34 Outdoor temperature sensor is disconnected for

RefrigerantTempSensorFault 35 Refrigerant temperature sensor is disconnected for

WaterTempSensorFault 36 Water temperature sensor is disconnected for

SetpointOffsetElecFault 37 Setpoint offset is disconnected for longer than

LowSpaceTemp 38 S pace temperature is lower than the active heating

HighSpaceTemp 39 Space te mp erature is higher than the active

LowDischargeTemp 40 The discharge temperature is lower than the low

High DischargeTemp 41 The discharge temperature is higher than the high

Meaning When Bit Is Set

network variable input transmits the water state:
hot or cold

nviFanSpeedCmdState

nviFanSpeedCmd

nviExtCmdOutput

longer than 30 seconds

longer than 30 seconds

longer than 30 seconds

longer than 30 seconds

longer than 30 seconds

30 seconds

setpoint by more than the offset for a time period
longer than the alarm delay

heating setpoint by more than the offset for a time
period longer than the alarm delay

limits setpoint for a time period longer than the
alarm delay

limits setpoint for a time period longer than the
alarm delay

LX Series Heat Pump Unit Controller User's Guide92

Table 36: nvoHPalarm (Part 2 of 2)

Programmatic Name Bit

Number

LowSpaceRH 42 The space humidity is lower than a setpoint by

HighSpaceRH 43 The space humidity is higher than a setpoint by

FanStateMismatch 44 The fan state is different than the fan output for a

PumpStateOff 45 The pump state is OFF , and the pump output is ON

AuxiliaryLowAlarm 46 The auxiliary alarm input is lower than the low limit

AuxiliaryHighAlarm 47 The auxiliary alarm input is higher than the low limit

Emergency 48 The Heat Pump Unit Controller is in emergency

Meaning When Bit Is Set

more than the humidity offset for a time period
longer than the alarm delay

more than humidity offset for a time period longer
than the alarm delay

time period longer than the alarm delay

for a time period longer than the alarm delay

setpoint for a time period longer than the alarm
delay

setpoint for a time period longer than the alarm
delay

mode

nvoHPstate

This network variable output sends the heat pump status. It provides configuration
errors and mode status.

Type: SNVT_state_64 (165). Format: UNVT_hp_state

Table 37: nvoHPstate (Part 1 of 2)

Programmatic Name Bit

Number

OutofService 0 The device is out of service There is no space

EmergencyMode 1 Emergency mode is ON It is received from the

HotWater 2 The water is hot
MecCoolingEnabled 4 Mechanical cooling is enabled This occurs when

CtrlOutputxOverridden 8–14 The heat pump object output is overridden
HwOutputxOverridden 15–21 The hardware output is overridden
DupDischrgTempCfgError 39 Duplicate discharge air temperature sensor

DupOutTempTempCfgError 40 Duplicate outdoor air temperature sensor

DupRefrigTempCfgError 41 Duplicate refrigerant temperature sensor

DupWaterTempCfgError 42 Duplicate water temperature sensor configuration

DupSpaceHumidCfgError 43 Duplicate space humidity sensor configuration

Meaning When Bit Is Set

temperature sensor configured, or nvislave is not
bound

nviEmergCmd or sent by the emergency contact

the outdoor temperature is higher than the
mechanical minimum outdoor temperature

configuration error

configuration error

configuration error

error

error

LX Series Heat Pump Unit Controller User's Guide 93

Table 37: nvoHPstate (Part 2 of 2)

Programmatic Name Bit

Number

DupCoilDiffPressCfgError 44 Duplicate coil differential pressure sensor

DupAuxAlarmCfgError 45 Duplicate auxiliary alarm sensor configuration error
DupFanStateCfgError 46 Duplicate fan state sensor configuration error
DupFanSpdSelCfgError 47 Duplicate fan speed selector sensor configuration

DupModeSelCfgError 48 Duplicate mode selector sensor configuration error
DupPumpStateCfgError 49 Duplicate pump state sensor configuration error
DupOccCntctCfgError 50 Duplicate occupancy contact sensor configuration

DupBypassCntctCfgError 51 Duplicate bypass contact sensor configuration

DupWindowCntctCfgError 52 Duplicate window contact sensor configuration

DupCoilFrostCfgError 53 Duplicate coil frost contact sensor configuration

DupEmergCntctCfgError 54 Duplicate emergency contact sensor configuration

FanSpeedCfgError 55 Fan speeds configuration error
NoFanOutputCfgError 56 No fan output configuration error
NoHeatOrCoolCfgError 57 No heat or cooling output configuration error
HeatValveCfgError 58 Heating valve configuration error
CoolValveCfgError 59 Cooling valve configuration error
HeatCoolValveCfgError 60 Heating and cooling valve configuration error
HeatStagesCfgError 61 Heating stages configuration error
CoolStagesCfgError 62 Cooli ng stages configuration error
RevValvWOCoolCfgError 63 Reversing valve without cooling stages

Meaning When Bit Is Set

configuration error

error

error

error

error

error

error

configuration error

nvoHwInput

These network variable outputs send the input value over the network with their
own changeable SNVT type. They are numbered following the input number
(nvoHwInput1, nvoHwInput2,...).

Type: Changeable type

nvoOccState

This network variable output sends the occupancy state used by the heat pump
object.

Type: SNVT_occupancy (109)

nvoSpaceTemp

This network variable output sends the space temperature used by the heat pump
object.

LX Series Heat Pump Unit Controller User's Guide94

Type: SNVT_temp_p (105)

nvoTerminalLoad

This network variable output sends the energy demand of the heat pump in
percentage. Positive values are cooling demand and negative values are heating
demand.

Type: SNVT_lev_percent (81)

nvoUnitStatus

This network variable output sends all of the following information
simultaneously:

• operating mode

• primary heating state as a percentage

• secondary heating state as a percentage

• cooling state as a percentage

• fan state as a percentage

• heat pump alarm state
Type: SNVT_hvac_status (112)

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Standard Network Variable Types (SNVT)

Listed here are some of the SNVTs more commonly used in the Heat Pump Unit
Controller configuration wizard.

SNVT_hvac_emerg (103 HVAC Emergency Mode)

Use for heating, ventilating, and air conditioning applications.

Table 38: SNVT_hvac_emerg

SNVT_hvac_emerg Description

Field emerg_t
Measurement Emergency Mode
Field Type Category Enumeration
Type Size 1 byte
Valid Type Range emerg_t
Type Resolution 1
Units N/A
Invalid Value EMERG_NUL
Raw Range emerg_t
Scale Factor N/A
File Name SNVT_EM.H
Default Value N/A

SNVT_hvac_mode (108)

Use for heating, ventilating, and air conditioning applications.

Table 39: SNVT_hvac_mode

SNVT_hvac_mode Description

SNVT Index 108
Measurement hvac_t
Field Type Category Enumeration
Type Size 1 byte
Valid Type Range hvac_t
Type Resolution 1
Units N/A
Invalid Value HVAC_NUL
Raw Range hvac_t
Scale Factor N/A
File Name SNVT_HV.H
Default Value N/A

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SNVT_hvac_status (112)

Use for heating, ventilating, and air conditioning applications.

Table 40: SNVT_hvac_status

SNVT_hvac_status Description

SNVT Index 112
Measurement HVAC Status
Field Type Category Structure
Type Size 12 bytes

Table 41: SNVT_hvac_status Structure

Field Measurement

mode hvac_t
heat_output_primary signed long
heat_output_secondary signed long
cool_output signed long
econ_output signed long
fan_output signed long
in_alarm unsigned short

Table 42: HVAC Status Mode

HVAC Status Mode Description

Field mode
Measurement hvac_t
Field Type Category Enumeration
Type Size 1 byte
Valid Type Range hvac_t
Type Resolution 1
Units N/A
Invalid Value HV_NUL
Raw Range hvac_t
Scale Factor N/A
File Name SNVT_HV.H
Default Value N/A

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Table 43: Primary Heat Output

Primary Heat Output Description

Field Heat_primary_output
Measurement Primary Heat Output
Field Type Category Signed Long
Type Size 2 bytes
Valid Type Range -163.840 – 163.830
Type Resolution 0.005
Units Percent of full scale
Invalid Value 32,767 (0x7FFF)
Raw Range -32,768 – 32,766

(0 x 8000 – 0 x 7FFE)

Scale Factor 5, -3, 0

S = a*10b*(R+c)

File Name N/A
Default Value N/A

Table 44: Secondary Heat Output

Secondary Heat Output Description

Field heat_output secondary
Measurement Secondary Heat Output
Field Type Category Signed Long
Type Size 2 bytes
Valid Type Range -163.840 – 163.830
Type Resolution 0.005
Units Percent of full scale
Invalid Value 32,767 (0x7FFF)
Raw Range -32,768 – 32,766
Scale Factor 5, -3, 0

S = a*10b*(R+c)

File Name N/A
Default Value N/A

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Table 45: Primary Cooling Output

Primary Cooling Output Description

Field cooling_output
Measurement Cooling Output
Field Type Category Signed Long
Type Size 2 bytes
Valid Type Range -163.840 – 163.830
Type Resolution 0.005
Units Percent of full scale
Invalid Value 32,767 (0x7FFF)
Raw Range -32,768 – 32,766

(0 x 8000 – 0 x 7FFE)

Scale Factor 5, -3, 0

File Name N/A
Default Value N/A

S = a*10b*(R+c)

Table 46: Economizer Output

Economizer Output Description

Field econ_output
Measurement Economizer Output
Field Type Category Signed Long
Type Size 2 bytes
Valid Type Range -163.840 – 163.830
Type Resolution 0.005
Units Percent of full scale
Invalid Value 32,767 (0x7FFF)
Raw Range -32,768 – 32,766

(0 x 8000 – 0 x 7FFE)

Scale Factor 5, -3, 0

S = a*10b*(R+c)

File Name N/A
Default Value N/A

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Table 47: Fan Output

Fan Output Description

Field fan_output
Measurement Fan Output
Field Type Category Signed Long
Type Size 2 bytes
Valid Type Range -163.840 – 163.830
Type Resolution 0.005
Units Percent of full scale
Invalid Value 32,767 (0x7FFF)
Raw Range -32,768 – 32,766

(0 x 8000 – 0 x 7FFE)

Scale Factor 5, -3, 0

File Name N/A
Default Value N/A

S = a*10b*(R+c)

Alarm State

Zero means that the unit is not in an alarm state. 255 (0xFF) means that alarming is
disabled. All other values, between 1 and 254, inclusive, mean that the unit is in
the alarm state. The values, between 1 and 254, are manufacturer specific as to
their meaning, but all represent an alarm state.

Table 48: Alarm State

Alarm State Description

Field month
Measurement In Alarm State
Field Type Category Unsigned Short
Type Size 1 byte
Valid Type Range -163.840 – 163.830
Type Resolution 0.005
Units Percent of full scale
Invalid Value 32,767 (0x7FFF)
Raw Range -32,768 – 32,766

(0 x 8000 – 0 x 7FFE)

Scale Factor 5, -3, 0

File Name N/A
Default Value N/A

S = a*10b*(R+c)

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