ModBus Protocol
DEFINITIONS
NO.
ITEM
DESCRIPTION
1
Data Flow
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.
2
Master - Slave
Modbus as master;
1# microboard as slave.
3
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.
4
Temperature (VSD)
Unit: 0.1 °C;
Actual temperature = Register value/10.
5
Pressure
Unit: kPa;
Actual pressure = Register value.
6
EEV Opening Degree
Unit: Step;
Actual EEV Opening Degree = Register value.
7
Fan Speed
Unit: RPM;
Actual Fan Speed = Register value.
8
Compressor Speed
Unit: 0.1 RPS;
Actual Compressor Speed = Register value/10.
9
Access Mechanism
BAS parameter setpoint may exceed unit default range and it is required
for BAS to read the setpoints from the microboard.
10
BAS Enable
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.
11
Start/Stop Status
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.
Cooke Industries - Phone: +64 9 579 2185 Email: [email protected] Web: www.cookeindustries.co.nz
