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IM 743-1

11

Integration

Integrating the Modbus Communications Module into a BAS involves three steps:

ƒ

 

Connecting the unit (node) to the network

ƒ

 

Addressing and establishing communications with the unit

ƒ

 

Configuring the unit to the building

Connecting to the Network

Network Topology

Standard Modbus network rules apply. The network is a daisy-chain of Modbus controllers including
all slaves and the master. The standard recommends that the network be terminated on each end with
the characteristic impedance of the network (about 120 ohms).  Follow the guidelines stated in the
Modbus specifications (see Reference Documents section for details.)

Addressing and Establishing Communications

Network Address and Baud Rate

Valid slave nodes addresses are in the range of 0 – 247 decimal. The individual slave devices are
assigned addresses in the range of 1 – 247. A master addresses a slave by placing the slave address in
the address field of the message. When the slave returns its response, it places its own address in the
response address field to let the master know which slave is responding. Address 0 is the broadcast
address. When the address is 0, all slaves respond to the message.
The network address for a MicroTech II Chiller Unit Controller is set in the unit controller keypad
display. The Modbus network address and data transmission rate (Baud Rate) is only available in the
keypad/display when the protocol is set to Modbus. You must set the protocol, network address
(ident number), and baud rate before you can communicate on the Modbus network.

To set the protocol, network address, and baud rate on a unit controller:

1.

 

Navigate to the SET UNIT SP menus.

2.

 

Navigate down the SET UNIT SP menus to the Protocol = screen.

3.

 

Change protocol to Modbus. You must enter the Manager Password of “2001.”

Note: 

Password screens listed are for Centrifugal Chillers.  Passwords/screens for other

models may be different.

4.

 

Two more parameters appear in the screen: one for the network address (ID Number or Ident
No.) and one for the data transmission rate (Baud Rate).

Note: 

See the appropriate Operation Manual for specific instructions for changing variables

with the keypad/display.

5.

 

Set the ID Number variable to the network address of the MicroTech II Chiller Unit Controller.
(See your network administrator for a network address.)

6.

 

Set the Baud Rate variable to the data transmission rate of the network.

Configuring the Unit Controller

The Modbus Communication Module and MicroTech II Chiller Unit Controller are configured
together at the factory. After you set up the network, the unit is ready to operate with the default

Summary of Contents for IM 743

Page 1: ...Cooled Global Scroll ACZ Air Cooled Scroll Condensing Unit WGZ Water Cooled Global Scroll AGS Air Cooled Global Screw WGS Water Cooled Global Screw NOTICE Use this manual to physically install the com...

Page 2: ...to the Network 11 Network Topology 11 Addressing and Establishing Communications 11 Network Address and Baud Rate 11 Configuring the Unit Controller 11 Service Information 13 Test Procedures 13 Repla...

Page 3: ...ir Cooled Scroll Chiller Installation Operation and Maintenance Manual www mcquay com IOMM WGZ McQuay International MicroTech II Water Cooled Scroll Chiller Installation Manual www mcquay com IOMM WPV...

Page 4: ...hange any information contained herein without prior notice The user is responsible for determining whether this software is appropriate for his or her application The following are trademarks or regi...

Page 5: ...ules These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment Operation of this equipment in a residential are...

Page 6: ...jor Components RS 485 Network Connetor 8 Pin Header Modbus Connector RS 485 Network Connector This connector connects the Modbus Communication Module to the RS 485 network Pin Function 1 Reference 2 I...

Page 7: ...rom the Serial Card slot if it hasn t already been removed Use a small screwdriver to pry the cover off from one end 4 Remove the plastic knockout in the cover 5 Figure 4 shows the Serial Card slot th...

Page 8: ...e of the network cable to Pin 2 of the connector plug b Connect the other wire to Pin 3 of the connector plug c No wire is connected to the remaining pin Figure 3 Serial Card Slot Location on Unit Con...

Page 9: ...IM 743 1 9 Figure 5 Network Cable Routing and Connections Figure 6 Network Connection Detail Net w ork Cab le Pin 3 Pin 2...

Page 10: ...the slot 10 Keeping the Modbus Communication Module level move it into the slot until you feel the connectors line up The correct position seems to be level toward the left side of the slot and down s...

Page 11: ...a MicroTech II Chiller Unit Controller is set in the unit controller keypad display The Modbus network address and data transmission rate Baud Rate is only available in the keypad display when the pr...

Page 12: ...d via the network or with the keypad display The appropriate Operation Manual provides default values and keypad operation The MicroTech II Chiller Modbus Protocol Information Document ED 15063 provid...

Page 13: ...ll does not respond contact the McQuay Controls Customer Support group at 866 4MCQUAY 866 462 7829 Replaceable Parts List Network Connection Plug Generic Replacement Parts If you lose this terminal bl...

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