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Part 7: Description for Modbus protocol interface
7.1. Device connection
Unit's electric control cabinet provides the RS485 communication interface convenient for the user's
monitoring the operation condition of the unit and system integrating. As long as the users follow the standard
MODBUS protocol and comply with the protocol point table provided by us, they can monitor the unit easily.
7.1.1. Communication Cable
1.
The A and B of the XTB2 terminal in 1# unit's electrical cabinet are the communication interfaces between the
unit and the computer. There must be a RS232/485 active or passive converter in the middle of them. The
communication line has polarity. A is connected to converter A (or +). B is connected to converter B (or-). Do not
connect them in a wrong way for fear of the occurrence of the Fault.
2
Communication distance shall be within 100 meters by using the 2×0.75mm
Communication distance shall be within 100-500 meters by using the 2×1.0mm
7.1.2. Connection Mode
Schematic Diagram of Connection Mode
7.2. Modbus Protocol
1 MODBUS RTU Protocol; CRC Check;
2 9600bps; 1-Bit Start Bit; 1-Bit Stop Bit; No Check Bit; 8-Bit Data Bit;
Definition of Temperature Data: 16-Bit Signed Digital (-32768 ~ + 32767); Actual Temperature = Temperature
3
Data/10; Unit:°C;
4 Buffer Size: 256 Bytes
HMI ON/OFF Command
HMI mode command
Set value for refrigeration
backwater temperature
Set value for heating
backwater temperature
Set value for refrigeration
outflow water temperature
Set value for heating outflow
water temperature
Cooke Industries - Phone: +64 9 579 2185
Description for Modbus protocol interface
Basic Description of the Protocol
System Content/Chiller Setpoint
3, 6, 16
0
0-Invalid; 1-On; 2-Off
0-refrigeration; 1-heating;
3, 6, 16
1
2-heat recovery; 8-water
pump cycle
3, 6, 16
2
°C, ×10
3, 6, 16
3
°C, ×10
3, 6, 16
4
°C, ×10
3, 6, 16
5
°C, ×10
77
Email: sales@cookeindustries.co.nz
2
shielded twisted pair;
2
shielded twisted pair;
Setting Range Shall Be the
Same as Unit's Set Value
Setting Range Shall Be the
Same as Unit's Set Value
Setting Range Shall Be the
Same as Unit's Set Value
Setting Range Shall Be the
Same as Unit's Set Value
Setting Range Shall Be the
Same as Unit's Set Value
Setting Range Shall Be the
Same as Unit's Set Value
Web: www.cookeindustries.co.nz
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