Modbus Tables - Air-To-Air Systems; Holding Registers - Procon A1M Installation Manual

11. Modbus tables – Air-To-Air systems
Some BMS controllers can only read Modbus Holding Registers, so the MelcoBEMS MINI (A1M) also exposes all
Discrete, Coil and Input Registers as Holding Registers. The Discrete Input registers and Input registers are not
writable so their equivalent Holding Register is read only and marked [READ ONLY].
Some BMS controllers may not be able to read signed register values (i.e. values which can be negative in value), so
the MelcoBEMS MINI (A1M) also exposes an unsigned version of those registers (these registers will not return a
negative value).
11.1.

Holding registers

Holding Registers are read using function code 03 and written to using either function code 06 or 16. Function code 06
is used when writing to a single holding register, function code 16 is used for writing to multiple holding registers in the
same command.
Register Name
Drive Mode
Temperature Setpoint
Fan Speed
Air Direction
Modbus Slave ID
BACnet Station ID
Holding Registers (Analogue Outputs)
Modicon
Address
Address
1 = Heating
2 = Humidity reduction
3 = Cooling
7 = Ventilation, clean air operation
8 = Auto Operation
9 = i-see heating operation
0 40001
10 = i-see humidity reduction
11 = i-see cooling
*
have no effect
Temperature value in °C multiplied by 10.
1 40002
e.g. value 200 = 20°C
0 = Auto
2 = Quiet
2 40003 3 = Weak
5 = Strong
6 = Very strong (SH i)
0 = Auto
1 = Position 1
2 = Position 2
3 40004 3 = Position 3
4 = Position 4
5 = Position 5
7 = Swing
Values 1 – 247 valid
4 40005
Values 1 -127 valid
Details
*
*
indicates a read only value, writing this value will
*
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