ModBus Protocol
DEFINITIONS
Communication Baud rate: 9600bps;
8-N-1: 1 start bit,1 stop bit, check bit-none, 8 data bits;
Modbus-RTU Protocol;
CRC: Cyclic Redundancy Check;
Hexadecimal data.
Modbus as master;
1# microboard as slave.
Temperature (Control
Panel)
Unit: 0.1 °C;
Actual temperature = Register value/10;
e.g.: Cool RT Setpoint Register value 0x0078 = 120, then the setpoint is
12.0 °C.
Unit: 0.1 °C;
Actual temperature = Register value/10.
Unit: kPa;
Actual pressure = Register value.
Unit: Step;
Actual EEV Opening Degree = Register value.
Unit: RPM;
Actual Fan Speed = Register value.
Unit: 0.1 RPS;
Actual Compressor Speed = Register value/10.
BAS parameter setpoint may exceed unit default range and it is required
for BAS to read the setpoints from the microboard.
The BAS Modbus addresses of subordinates are set through HMI;
Set the corresponding parameters in HMI to enable and disable the BAS
Start/Stop and Operating Mode functions.
The Start/Stop Command (Register value = 0) is only used to start/stop
the unit;
Actual Start/Stop Status is accessible by reading Register value = 100.
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