Specifications

4P357732-1 – 2014.04 Page 21 of 58
2.3.2 Monitor and operate units from the BMS
Input registers of each DIII unit: 30001 and higher
The input registers will contain the status of the connected DIII units.
In case the DIII communication is interrupted (see Input registers 30006 till 30009): then the last
communicated values will remain, until the DIII communication is restored.
Status changes are communicated continuously to the input registers, meaning the input registers will
contain the actual values.
Holding registers of each DIII unit: 42001 and higher
- Writing instructions to change a unit status (Preset Single or Multiple Registers)
When a value is written to a holding register, it will be communicated to the DIII units.
Attention:
Modbus Interface DIII sends the command to a unit when the value of a Holding Register is
changed. Especially in case that indoor units are operated from the user interface, the BMS should
always get the status of indoor units and copy the received status to the Holding Registers.
Note: at start-up of the system (See 2.3.1 System initialisation) and the initial discovery of the DIII
connected units, the Modbus Interface DIII put the actual status in the holding registers. (Remark: not
during rediscovery.)
Change on/off
Return: status
Check communication status (30006-9)
BMS
Modbus Interface DIII
DIII unit
BMS checks
communication
status
Copy:
BMS gets all DIII
units current
status by reading
the input
registers and
copies to the
related bits (pre-
set) to the
holding registers
Return values
Get DIII unit status (input registers)
Preset DIII unit status to the holding register
Command:
BMS changes a
value in the
holding registers
Preset On/Off bit to the holding register