Manual Supplement
Model Number: 8636-N2
Product/System Title: Room Pressure Controller with Reheat
Control and N2 Communications Protocol
Contents of this manual supplement include:
1) Sequence of Operation
2) Menu configuration
3) Software items deleted
4) Variable Map
5) Description of variables
6) Wiring Diagram
N2 communications are installed on the Model 8636-N2 room pressure controllers. This document
provides the technical information needed for the host DDC system to communicate with 8636
units. This document assumes the programmer is familiar with the N2 protocol. Further technical
assistance is available from TSI if your question is related to TSI interfacing to a DDC system. If
you need further information regarding N2 programming in general, please contact Johnson
Controls.
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Sequence of Operation
The Model 8636-N2 measures the room pressure differential and receives temperature information
from the temperature sensor. The 8636-N2 control algorithm modulates the supply and general
exhaust air to provide adequate supply air while maintaining the room pressure differential and
temperature control.
In occupied mode, the Model 8636-N2 has two supply flow set points: ventilation and temperature.
The ventilation setpoint is the minimum supply flow for the space, used when the heating and
cooling loads are met. The temperature supply set point is a higher flow, required to meet an
increased cooling load in the lab.
Laboratory temperature is continuously transmitted to the Model 8636-N2. When the laboratory
temperature is satisfied, the ventilation set point is maintained, unless additional supply air is
required for the room pressure balance. When the space temperature is more than 1°F above the
temperature setpoint, the 8636-N2 slowly will increase the supply air volume, to a maximum of the
temperature minimum supply flow, until the space temperature returns to setpoint. When the space
temperature is more than 1°F below the temperature setpoint, the 8636-N2 slowly will decrease the
supply air volume, to a minimum of the ventilation minimum supply flow, until the space
temperature returns to setpoint. If the supply volume is at the ventilation minimum supply flow, the
Model 8636-N2 will modulate the reheat valve to provide the necessary heating.
In unoccupied mode, the supply flow will remain at the unoccupied supply flow rate.
Supply air volumes will rise above the minimum setpoints, under all conditions, as required to
maintain space pressurization. Temperature control and occupied/unoccupied modes will only
affect the minimum supply flows, which are used, for example, when fume hood sashes are
lowered.
NOTE: The 8636-N2 will not allow the temperature minimum supply volume to be less than the
ventilation minimum supply volume.
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Menu Configuration
SETPOINTS ALARM CONFIGURE CALIBRATION
SETPOINT
REM SETPOINT
UNOCC SETP
VENT MIN SET
TEMP MIN SET
TEMP SETP
CONTROL SUPPLY FLOW
SPEED
SENSITIVITY
CONTROL SIG
Kc VALUE
Ti VALUE
TEMP OUTPUT
TEMP CONTROL
TEMP Kc VAL
LOW ALARM
HIGH ALARM
REM LOW ALM
REM HIGH ALM
MIN SUP ALM
ALARM RESET
AUDIBLE ALM
ALARM DELAY
DOOR DELAY
MUTE TIMEOUT
SP1 DCT REA
SP2 DCT REA
SP1 FLO ZERO
SP2 FLO ZERO
FLO STA TYPE
TOP VELOCITY
SP LOW SETP
SP HIGH SETP
SP1 LOW CAL
SP1 HIGH CAL
SP2 LOW CAL
SP2 HIGH CAL
RESET CAL
UNITS
NET ADDRESS
ACCESS CODES
SENSOR SPAN
ELEVATION
TEMP CAL
DIAGNOSTICS
CONTROL SUP
CONTROL EXH
CONTROL TEMP
SENSOR INPUT
SENSOR STAT
DOOR SWITCH
UNOCC SWITCH
SUP1 FLOW IN
SUP2 FLOW IN
TEMP INPUT
ALARM RELAY
Software Item Deleted
The following software item has been deleted from the 8636-N2:
Menu Item
SETPOINTS MIN SUP DAMP
MAX SUP DAMP
MIN EXH DAMP
MAX EXH DAMP
CONFIGURE NET PROTOCOL
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Variable Map
NPT NPA UNITS1 DESCRIPTION
AI 1 ft/min, m/s,
in. H2O, Pa,
mm H2O
AI 2 CFM, l/s Total Supply Flow Rate
AI 3
°F, °C
AI 4 ft/min, m/s,
in. H2O, Pa,
mm H2O
AI 5 CFM, l/s Minimum Supply Setpoint
AI 6 # Supply Control Output
AI 7 # Exhaust Control Output
AI 8 # Temperature Control Output
BI 1 Low Room Pressure Alarm 0=Normal
BI 2 High Room Pressure Alarm 0=Normal
BI 3 Min. Flow Alarm 0=Normal
BI 4 Emergency Mode 0=Normal
BI 5 Room Mode 0=Main
BI 6 Occupied/Unoccupied Mode 0=Occupied
BI 7 Data Error 0=Normal
AO 1 ft/min, m/s,
in. H2O, Pa,
mm H2O
AO 2 ft/min, m/s,
in. H2O, Pa,
mm H2O
AO 3 ft/min, m/s,
in. H2O, Pa,
mm H2O
AO 4 ft/min, m/s,
in. H2O, Pa,
mm H2O
AO 5 CFM, l/s Min. Supply Flow Alarm Setpoint
Room Pressure Value
Temperature
Control Setpoint
1=Low Alarm
1=High Alarm
1=Low Flow Alarm
1=Emergency Mode
1=Remote
1=Unoccupied
1=Data Error
Low Alarm Setpoint
High Alarm Setpoint
Remote Low Alarm Setpoint
Remote High Alarm Setpoint
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NPT NPA UNITS1 DESCRIPTION
AO 6 ft/min, m/s,
Main Pressure Setpoint
in. H2O, Pa,
mm H2O
AO 7 CFM, l/s Remote Pressure Setpoint
AO 8 CFM, l/s Minimum Ventilation Rate Supply Flow Setpoint
AO 9 CFM, l/s Minimum Temperature Supply Flow Setpoint
AO 10 CFM, l/s Unoccupied Mode Minimum Supply Flow Setpoint
AO 11
°F, °C
Temperature Setpoint
AO 12 # Units 0=Feet per minute
1=Meters per second
2=Inches of H2O
3=Pascals
1
Units will correspond with choice in UNITS variable (AO #12). Flow rates will either be CFM or l/s, based on
whether UNITS variable is set for an english or metric unit type.
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Description of Variables
NPT - Network Point Type
Variables are defined as analog inputs, binary inputs, and analog outputs. Analog inputs are current
control parameters and items that the controller is measuring. Binary inputs represent controller
states. Analog outputs are the programmable setpoints for the isolation room pressure controller
and monitor. These setpoints can be changed through the keypad or by overriding the current
setpoint.
NPA - Network Point Address
Address of the desired point.
Change of Status (COS) - Room Pressure Analog Input
The 8636-N2 has the ability to change control setpoints locally. The alarm setpoints need to be
based on the controller’s control setpoint (AI #4). For example the setpoint could go from -0.002
“H2O to +0.001 “H2O. If the COS alarm setpoints are not changed to accommodate you could get
low alarm or low warning messages when the unit is working correctly. If these alarm points are
set outside of the negative and positive setpoint values, incorrect alarm messages can be prevented.
Override Analog Input Command
Analog Input values can be set using the override command. These values will be reset to the
correct items when the Override is released. There is not a time-out on the override command.
Override Binary Input Command
Overriding a 1 to Emergency binary inputs enables that mode. To release the controller from
emergency state, override a 0 to the Emergency input or press either the emergency or reset key.
Releasing the override will return the controller to the Normal state. If the 8636-N2 had been put
into Emergency mode from the keypad, then it cannot be cleared remotely.
Overriding a 1 to Room Mode binary inputs enables Remote mode. To release the controller from
remote state, override a 0 to the Room Mode. Releasing the override will return the controller to
the Normal state.
Overriding a 1 to the Occupied/Unoccupied Mode binary inputs enables the unoccupied mode. To
release the controller from the unoccupied state, override a 0 to the Occupied/Unoccupied Mode.
The Occupied/Unoccupied Mode can only be accessed through N2 communications.
The alarm and data error variables can be overridden, but this will not affect the controller.
Overriding the low alarm variable will result in a change of status, but will not put the controller
into low alarm mode. The local alarm modes can only be controlled locally. Only override these
variables for diagnostic purposes, and release them for normal operation.
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Binary Input Data Error
Data Error binary inputs are used to indicate if something has gone wrong with the controller. Data
Error indicates when some of the data stored on the device has been corrupted. The calibration and
setpoint values should be checked on the controller.
Override Analog Output Command
The analog output variables can be overridden to change their values. The overridden value will be
checked for validity. If invalid, the override command will be ignored, and the value will not
change. The override flag will not be set when the value is ignored. The override command will be
cleared when the variable is reset in the menus. The variable will not reset with the release
command.
Supported Commands
Command Response
Request Device ID Returns 0x10
Synchronize Time Command Acknowledged. There Is No Internal Clock To
Synchronize.
Poll Without/With Ack Message Any Change Of Status Is Returned
Read Analog Input Command Variable Value
Read Binary Input Command Variable Value
Read Analog Output Command Variable Value
Write Analog Input Acknowledge
Write Binary Input Acknowledge
Write Analog Output Acknowledge
Override Analog Input Command Acknowledge
Override Binary Input Command Acknowledge
Override Analog Output Command Acknowledge
Override Release Request Acknowledge
Identify Device Type Command Returns 0x10h
Note: Poll Without/With Ack Message will need to be sent twice in order to receive all of the
possible change of status variables.
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Wiring Diagrams
MODEL 8636-N2 PRESSUR E CONTROLLER
MODEL 8636-N2
WIRING DIAGRAM - ELECTRIC
WIRING DIAG RAM - ELEC TRIC
28
27
26
25
24
23
22
21
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MODEL 8636-N2 PRESSURE CONTROLLER
MODEL 8636-N2
WIRING DIAGRAM - PNEUMATIC
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