Modbus Tables - Air-To-Water Systems; Holding Registers - Procon MelcoBEMS MINI Installation Manual

Modbus tables – Air-To-Water 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 A1M also exposes an unsigned version of those registers (these registers will not return a negative value).
11.5.

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
Modbus Slave ID
Modbus RS-485 Baud Rate
RS-485 Parity Type
Fault/Error Code (hex)
[READ ONLY]
A1M Firmware Version
[READ ONLY]
Modbus Comms Counter
[READ ONLY]
Fault Code (decimal)
[READ ONLY]
System Type Detected
[READ ONLY]
System On/Off
Operating Mode
Page 22 of 47
Holding Register (Analogue Output)
Modicon
Addr
Address
4 40005 Values 1 – 247 valid
0 = 9600
1 = 1200
2 = 2400
3 = 4800
4 = 9600
5 = 14400
5 40006
6 = 19200
7 = 28800
8 = 38400
9 = 56000
10 = 57600
11 = 115200
0 = None
6 40007 1 = Even
2 = Odd
0x8000 = No error
0x6999 = Bad communication with unit
9 40010
(Refer to indoor unit documentation for description
of other fault code values)
10 40011 A1M firmware version
Value of a counter which increments upon every
11 40012 valid Modbus command received. Counter is reset
to zero when value exceeds 65535.
8000 = No error
6999 = Bad communication between A1M and unit
12 40013
(Refer to unit documentation for description of other
fault code values)
0 = A1M has detected an ATA unit connected
13 40014
1 = A1M has detected an ATW system connected
0 = System OFF
1 = System ON
25 40026
2 = Emergency Run (read only value)
3 = Test Run (read only value)
0 = Stop
1 = Hot Water
26 40027
2 = Heating
3 = Cooling
Details
Applicable Unit Type
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