Danfoss VLT 2800, VLT 6000, VLT 8000 Operating guide

Operating Instructions

Modbus RTU

VLT® 2800

VLT® 6000

VLT® 8000

VLT®2800, VLT®6000 HVAC and VLT®8000 AQUA Modbus RTU

■ Contents

Overview

Introduction ............................................................................................................ 6

About This Manual ................................................................................................. 6

Assumptions .......................................................................................................... 6

What You Should Already Know ............................................................................. 6

Modbus RTU Overview .......................................................................................... 6

VLT 2800, VLT 6000 and VLT 8000 with Modbus RTU ........................................... 7

............................................................................................................. 6

Installation and Setup .................................................................................. 8

Network Connection ............................................................................................. 8

Hardware Setup VLT 2800 ..................................................................................... 9

Hardware Setup VLT 6000 and VLT 8000 ............................................................... 9

EMC Precautions ................................................................................................... 9

Modbus RTU Programming ....................................................................... 10

VLT 2800 Parameter Settings for Modbus Communication ..................................... 10

VLT 6000 Parameter Settings for Modbus Communication ..................................... 12

Installation and Set-up VLT 8000 ............................................................................ 13

VLT 8000 Parameter Settings for Modbus Communication ..................................... 13

Network Configuration ................................................................................. 14

Remote Terminal Unit ............................................................................................. 14

Modbus RTU Message Framing Structure .............................................................. 14

Parameter Handling ....................................................................................... 16

Parameter Handling ................................................................................................ 16

Storage of Data ...................................................................................................... 16

Process Data ......................................................................................................... 20

Status Coil Maps .................................................................................................... 20

Control Word Bit Descriptions for VLT 2800 ............................................................ 20

Status Word Bit Description for VLT 2800 ............................................................... 21

Control Word Bit Descriptions VLT 6000 / VLT 8000 ............................................... 23

Status Word Bit Descriptions VLT 6000 / VLT 8000 ................................................ 25

Serial communication reference .............................................................................. 26

Present output frequency ....................................................................................... 26

Supported Modbus RTU Function C odes ......................................... 28

Exception Codes ............................................................................................. 31

Exception Code Tables .......................................................................................... 31

Appendix A - Examples ............................................................................... 32

MG.10.S2.02 - VLT is a registered Danfoss trademark

VLT®2800, VLT®6000 HVAC and VLT®8000 AQUA Modbus RTU

■Software Version VLT 2800, VLT 6000 and VLT 8000

VLT 2800 Series

Operating instructions Software version: 2.8x

These operating instructions can be used for all VLT 2800 Series frequency converters with software version 2.8x. The software version number can be seen from parameter 640 Software version no.

195NA009.17

VLT 6000 HVAC

Operating Instructions Software version: 3.0x

These Operating Instructions can be used for all VLT 6000 HVAC frequency converters with software version 3.0x. The software version number can be seen from parameter

624.

175ZA691.14

MG.10.S2.02 - VLT is a registered Danfoss trademark

VLT®2800, VLT®6000 HVAC and VLT®8000 AQUA Modbus RTU

VLT 8000 AQUA

Operating Instructions Software version: 1.5x

176FA145.13

RTU

These Operating Instructions can be used for all VLT 8000 AQUA frequency converters with software version 1.5x. The software version number can be seen from parameter 624

Software version no.

■High Voltage Warning

Rotating shafts and electrical equipment can be hazardous. Therefore, it is stron

recommended that all electrical work conform to National Electrical Code (NEC) and all local regulations. Installation, s should be performed only by qualified personnel.

Motor control equipment and electronic controls are connected to hazardous line voltages. When servicing

■Warnings Against Unintended Start

1. While t

2. During programming of parameters, the motor

he frequency converter is connected to the AC line, the motor can be brought to a stop by means of external switch closures,

rial bus commands or references. If personal

se safety considerations make it necessary to ensure that no unintended start occurs, these stops are not sufficient.

may start. Be certain that no one is in the

tart-up and maintenance

gly

frequency converters and electronic controls, there will be exposed components at or above line pote Extreme care should be taken to protect against shock. Stand on an insulating pad and make it a habit to use only one hand when checking component work with another person in case of an emergency. Disconnect power whenever possible to check controls or to perform maintenance. Be properly grounded. Wear safety glasses whenever working on electric control or rotating equipment.

area of the motor or frequency converter driven

pment when changing parameters

equi

3. A motor that has been stopped may start unexpectedly if faults occur in the electronics

the frequency converter, or if an overload, a

of fault in the supply AC line or a fault in the motor connection or other fault clears.

f the "Local/Hand" key is activated, the motor

4.I can only be brought to a stop by means of the "Stop/Off" key or an external safety interlock.

sure equipment is

ntial.

s. Always

Safety - Modbus

■Electrostatic discharge (ESD)

Electronic components are sensitive to electrostatic discharge (ESD). ESD can

reduce performance or destroy sensitive electronic components. Follow proper ESD procedures during installation or servicing to prevent damage.

MG.10.S2.02 - VLT is a registered Danfoss trademark

VLT®2800, VLT®6000 HVAC and VLT®8000 AQUA Modbus RTU

VLT 2800

It can be extremely dangerous to touch the electrical parts even when the mains

supply has been disconnected.

Also ensure that other voltage inputs are disconnected from load sharing through the

DC bus.

Wait at least 4 minutes after the input power has been removed before servicing the

drive.

195NA139.10

VLT 6000 HVAC

Warning:

Touching the electrical parts may be fatal - even after the equipment has been disconnected from mains.

Using VLT 6002 - 6005, 200-240 V: Wait at least 4 minutes Using VLT 6006 - 6062, 200-240 V: Wait at least 15 minutes Using VLT 6002 - 6005, 380-460 V: Wait at least 4 minutes Using VLT 6006 - 6072, 380-460 V: Wait at least 15 minutes Using VLT 6102 - 6352, 380-460 V: Wait at least 20 minutes Using VLT 6400 - 6550, 380-460 V: Wait at least 15 minutes Using VLT 6002 - 6006, 525-600 V: Wait at least 4 minutes Using VLT 6008 - 6027, 525-600 V: Wait at least 15 minutes

Using VLT 6032 - 6275, 525-600 V: Wait at least 30 minutes

175HA490.11

MG.10.S2.02 - VLT is a registered Danfoss trademark

VLT®2800, VLT®6000 HVAC and VLT®8000 AQUA Modbus RTU

VLT 8000 AQUA

Touching the electrical parts may be fatal - even after the equipment has been disconnected from line.

Warning:

VLT 8006-8062, 200-240 V: wait at least 15 minutes VLT 8006-8072, 380-480 V: wait at least 15 minutes VLT 8102-8352, 380-480 V: wait at least 20 minutes VLT 8450-8600, 380-480 V: wait at least 15 minutes VLT 8002-8006, 525-600 V: wait at least 4 minutes VLT 8008-8027, 525-600 V: wait at least 15 minutes VLT 8032-8300, 525-600 V: wait at least 30 minutes

176FA159.12

RTU

Safety - Modbus

MG.10.S2.02 - VLT is a registered Danfoss trademark

■Overview

VLT®2800, VLT®6000 HVAC and VLT®8000 AQUA Modbus RTU

■Introduction

These operating instructions provide comprehensive instructions on the installation and set up of the

Modbus RTU for VLT

and VLT

8000 AQUA Frequency Converter to

2800, VLT®6000 HVAC

communicate over a Modbus network.

For specific information on installation and operation

2800 6000

of the frequency converter, refer to the VLT Operating Instructions, MG.28.AX.YY / VLT HVAC Operating Instructions, MG.61.AX.YY /

8000 Operating Instructions, MG.80.AX.YY.

VLT

■About This Manual

These operating instructions are intended to be used for both instruction and reference. It only briefly touches on the basics of the Modbus protocol whenever necessary to gain an understanding of the Modbus RTU.

These operating instructions are also intended to serve as a guideline when you specify and optimise your communication system. Even if you are an experienced Modbus programmer, it is suggested that you read these operating instructions in its entirety before you start programming since impor information can be found in all sections.

■Assumptions

These operating instructions assume that you have a controller that supports the interfaces

in this document and that all the requirements stipulated in the controller, as well as the frequency converter, are strictly observed, along with all l

imitations therein.

tant

other devices, and how errors will be detected and reported. It establishes a common format for the layout and contents of message fields.

During communications on a Modbus RTU network, the protocol determines how each controller will know its device address, recognise a message addressed to it, determine the kind of action to be taken, and extract any data or other information contained in the message. If a reply is required, the controller will construct the reply message and send it.

Controllers communicate using a master-slave technique in which only one device (the master) can initiate transactions (called queries). The other devices (slaves) respond by supplying the requested data to the master, or by taking the action requested in the query.

The master can address individual slaves, or can initiate a broadcast message to all slaves. Slaves return a message (called a response) to queries that are addressed to them individually. Responses are not returned to broadcast queries from the master.

The Modbus RTU protocol establishes the format

for the master’s query by placing into it the device

(or broadcast) address, a function code defi

ning

the requested action, any data to be sent, and an

error-checking field. The slave’s response message

is also constructed using Modbus pro

tocol. It contains fields confirming the action taken, any data to be returned, and an error-checking field. If an error occurred in receipt of the m

essage, or if the slave is unable to perform the requested action, the slave will construct an error message and send it in response or a time-out wi

ll occur.

■What You Should Already Know

The Modbus RTU is designed to communicate with any controller that supports the interfaces defined in this document. It is assumed that yo

u have full knowledge

of the capabilities and limitations of the controller.

■Modbus RTU Overview

Modbus RTU (Remote Terminal Unit) protocol defines a message structure that co

ntrollers will recognise and use, regardless of the type of physical networks over which they communicate. It describes the process a controller use

s to request access to another

device, how it will respond to requests from the

MG.10.S2.02 - VLT is a registered Danfoss trademark

VLT®2800, VLT®6000 HVAC and VLT®8000 AQUA Modbus RTU

■VLT 2800, VLT 6000 and VLT 8000 with Modbus RTU

The frequency converter communicates in Modbus RTU format over an EIA-485 (formerly RS-485) network. Modbus RTU allows access to the frequency

converter’s Control Word and Bus Reference.

The Control Word allows the Modbus master to control several important functions of the frequency converter:

• Start

• Stop the frequency converter in several ways:

Coast stop Quick stop DC Brake stop Normal (ramp) stop

• Reset after a fault trip

• Run at a variety of preset speeds

• Runinreverse

• Change the active setup

• Control the frequency converter’s two built-in relays

The Bus Reference is commonly used for speed control.

It is also possible to access the parameters, read their values, and, where possible, write values to them. This permits a range of control possibilities,

including controlling the frequency converter’ssetpoint

when its internal PID controller is used.

Overview

MG.10.S2.02 - VLT is a registered Danfoss trademark

VLT®2800, VLT®6000 HVAC and VLT®8000 AQUA Modbus RTU

■Installation and Setup

Modbus RTU is a transmission protocol developed for process control systems. The Modbus standard does not specify the physical interface for the protocol i.e. a number of different interfaces can be chosen. The Modbus RTU protocol is based on the build-in RS-485 (EIA-485) interface. RS-485 is a two-wire bus-interface that allows multi-drop network topology i.e. nodes can be connected as a bus, or via drop cables from a common trunk line. A total number of 32 nodes can be connected to one Modbus RTU network segment, and a total of 247 nodes in a network are supported. Network segments are divided with repeaters. Please note that each repeater counts for a node

in each segment it’sinstalled.

Every node connected to the same network must have an unique nodes address, across all segments.

Every segment must be terminated in both ends, either with the termination switches (switch 2 &

3) of the VLT 6000 / VLT 8000 or with a biased termination resistor network.

It is very important to have a low impedance ground connection of the screen, also at high frequencies. This can be obtained by connecting a large surface of the screen to ground, for example by means of a cable clamp or a conductive cable gland. Particularly in installation where there is long cable lengths, it can be necessary to apply potential equalizing cables to ensure same ground potential throughout the network. To prevent impedance mismatch, always use cable of same type across the entire network. When connecting a motor to the frequency converter, make sure always to use screened motor cable.

Address range:

1-247

Baud Rate:

300 - 9600 bps

Cable:

Screened twisted pair (STP) Impedance: 120 Ohm

For bus-cabling always use cable of screened twisted pair type (STP), and make sure to follow good common installation practice. Make sure the screen of the Modbus RTU cable must always be connected to ground at all nodes.

■Network Connection

Connect the frequency converter to the Modbus RTU in accordance with the following procedure (see Figure 1).

1. Connect signal wires to terminal 68 (P+) and

terminal 69 (N-) on main control board of the frequency converter.

2. The shield of the cable must be connected

to the cable clamps.

NB!:

It is recommended to use shielded, twisted-pair cables to reduce noise between conductors.

Cable length:

Max. 1200 m (including drop lines) Max. 500 m station-to-station

Figure 1 Network Terminal Connection

MG.10.S2.02 - VLT is a registered Danfoss trademark

VLT®2800, VLT®6000 HVAC and VLT®8000 AQUA Modbus RTU

■Hardware Setup VLT 2800

The VLT 2800 control card does not have build-in termination network for RS 485. To terminate with the

■Hardware Setup VLT 6000 and VLT 8000

A terminator dip switch on the main control board of the frequency converter is used to terminate the Modbus RTU bus. The switch positions shown in Figure 2 demonstrate the factory setting. Table 1 lists the switch functions and settings required for Modbus RTU operation.

correct impedance in the network the following resistors shouldbeappliedatthefirstandthelaststation.

Figure 2 Terminator Switch Factory Setting

NB!:

Factory setting for DIP Switch is on.

Table 1 Terminator Switch Functions and Modbus RTU Switch Setting

Switches 2 & 3 Used for terminating an RS-485 interface. On first and last devices in a multiple device

network, or on the only device in a single device network, switches 2 and 3 must be ON. On all other devices in a multiple device network, 2 and 3 must be OFF.

NB!:

Terminator switch positions must be set correctly in accordance with Table 1 for proper Modbus RTU serial communication.

■EMC Precautions

The following EMC precautions are recommended in order to achieve interference-free operation of the Modbus RTU network.

NB!:

Relevant national and local regulations, for example regarding protective earth connection, must be observed.

The Modbus RTU communication cable must be kept away from motor and brake resistor cables to avoid coupling of high frequency noise from one cable to the other. Normally a distance of 200 mm (8 inches) is sufficient, but it is generally recommended to keep the greatest possible distance between the cables, especially where cables run in parallel over long distances. If the Modbus RTU cable has to cross a motor and brake resistor cable they must cross each other at an angle of 90 degrees.

Setup

Installation and

MG.10.S2.02 - VLT is a registered Danfoss trademark

VLT®2800, VLT®6000 HVAC and VLT®8000 AQUA Modbus RTU

■VLT 2800 Parameter Settings for Modbus

Communication

Using the Modbus RTU Protocol requires setting of the below listed parameters.

NB!:

Please make sure that par. 512 Te le gr am Profile is set to FC PROFILE.

See the VLT 2800 Operating Instructions MG.28.AX.YY for details on selecting and changing parameter values, if necessary.

500 Address

(BUS ADDRESS)

Value:

Parameter 500 Protocol = FC protocol [0]

0 - 247

Parameter 500 Protocol = Metasys N2 [1]

1 - 255

Parameter 500 Protocol = MODBUS RTU [3]

1 - 247

Function:

This parameter allows the allocation of an address to each frequency converter in a serial communication network.

Description of choice:

The individual frequency converter must be allocated a unique address. If the number of units connected (frequency converters + master) is higher than 31, a repeater must be used. Parameter 500 Address cannot be selected via the serial communication, but must be preset via the control unit.

✭ 1

Description of choice:

The frequency converter’s transmission speed

must be set at a value corresponding to the transmission speed of the master. Parameter 501 Baudrate cannot be selected via the serial port, but must be preset via the operating unit.

561 Protocol

(PROTOCOL)

Value:

✭FC protocol (FC PROTOCOL)

Metasys N2 (METASYS N2) MODBUS RTU (MODBUS RTU)

Function:

There is a choice of three different protocols.

Description of choice:

Select the required control word protocol.

570 Modbus parity and message framing

(M.BUS PAR./FRAME)

Value:

(EVEN/1 STOPBIT) (ODD/1 STOPBIT)

✭(NO PARITY/1 STOPBIT)

(NO PARITY/2 STOPBIT)

Function:

This parameter sets up the drive’sModbusRTU

interface to communicate properly with the master controller. The parity (EVEN, ODD, or NO PARITY) must be set to match the setting of the master controller.

[1] [2] [3]

[0] [1] [2] [3]

Description of choice:

501 Baudrate

(BAUDRATE)

Value:

300 Baud (300 BAUD) 600 Baud (600 BAUD) 1200 Baud (1200 BAUD) 2400 Baud (2400 BAUD) 4800 Baud (4800 BAUD)

✭9600 Baud (9600 BAUD)

Function:

This parameter is for programming the speed at which data is transmitted via the serial port. Baud rate is defined as the number of bits transmitted per second.

✭ = factory setting. () = display text [] = value for use in communication via serial communication port

[0] [1] [2] [3] [4] [5]

Select the parity that matches the setting for the Modbus master controller. Even or odd parity is sometimes used to allow a transmitted word to be checked for errors. Because Modbus RTU uses the more efficient CRC (Cyclic Redundancy Check) method of checking for errors, parity checking is seldom used in Modbus RTU networks.

MG.10.S2.02 - VLT is a registered Danfoss trademark

VLT®2800, VLT®6000 HVAC and VLT®8000 AQUA Modbus RTU

571 Modbus communications timeout

(M.BUS COM.TIME.)

Value:

10 ms - 2000 ms

Function:

This parameter determines the maximum amount

of time that the drive’sModbusRTUwillwait

between characters that are sent by the master controller. When this amount of time expires, the

drive’s Modbus RTU interface will assume that it

has received the entire message.

Description of choice:

Generally, the value of 100 ms is sufficient for Modbus RTU networks, although some Modbus RTU networks may operate on a time-out value as short as 35 ms.

If this value is set too short, the drive’sModbusRTU

interface may miss a part of the message. Since the CRC check will not be valid, the drive will ignore the message. The resulting retransmissions of messages will slow communications on the network. If this value is set too long, the drive will wait longer than necessary to determine that the message is

completed. This will delay the drive’s response to the

message and possibly cause the master controller to time out. The resulting retransmissions of messages will slow communications on the network.

✭ 100 ms

✭ = factory setting. () = display text [] = value for use in communication via serial communication port

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Modbus RTU

Programming

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