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58000081 Iss 01
10. BMS Connection MODBUS Protocol
9.1 BMS Connection
The heater is compatible with BMS systems using
MODBUS protocol.
The connection to BMS system can be made using
one of the RJ45 connectors.
Only one means of control can be used at the
same time. If BMS is used to control the heater, the
colour screen controller must not be used.
The BMS can control fan speed and heat output
and also read and report the heater status.
Speed can be set in the range of 600 - 1700RPM in
1RPM steps. If the speed is set below 600RMP, the
heating element is automatically disabled. Care
has to be taken when selecting speed. The fan
speed should be always correct for the selected
heat output. If the speed is too low, the heater can
overheat.
Heat output can be set in the range of 0 - 100% in
1% steps.
9.2 MODBUS Protocol
The DIP switches 1, 2 and 3 are used
to configure each air curtain with a
unique address.
R
J45 cable can be used to network up to 7 air cur-
tains in a daisy-chain configuration.
DIP switch setting 000X is reserved for when a con-
troller or BMS is not used.
All possible addresses:
RS485 serial half-duplex interface
MODBUS RTU
9600 baud
8 bits
1 start bit
no 2 stop bits
‘mark’ 1 stop bit
Supported MODBUS function codes:
0x03 read multiple input registers
0x04 read multiple holding registers
0x06 write single holding register
0x10 write multiple holding registers
16 Bit Input Registers:
1 Status
2 Temp 1
3 Temp 2
4 Temp Heatsink
5 Temp External
6 External Switches
Temperatures are formatted as 16 bit signed integers.
Units are sixteenths of a degrees Celsius, as used by
DS18B20 temperature sensors. The hex value 0xF000 is
used to denote an invalid reading.
The status register uses bits to indicate faults:
Bit 0 - overheat
Bit 1 - heatsink overheat
Bit 2 - temp sensor 1
Bit 3 - temp sensor 2
Bit 4 - heatsink temp sensor
Bit 5 - remote temp sensor
Bit 6 - L2 on current low
Bit 7 - L2 off current high
Bit 8 - L3 on current low
Bit 9 - L3 off current high
Bit 10 - motor PSU
Bit 11 - motor
Bit 12 - MCU
Bit 13 - connection
Bit 14 - 12V auxiliary power
Bit 15 - main PCB relay
External switches register uses bits to show the state
of switches:
Bit 0 - Switch 1
Bit 1 - Switch 2
Bit 2 - Switch 3
Bit 3 - Switch 4
16 Bit Holding Registers:
1 RPM (units revolutions per minute)
2 Power (units percentage 0
–
100)
RPM must be set to at least 600, otherwise heating is
disabled.
1
100X
2
010X
3
110X
4
001X
5
101X
6
011X
7
111X
Main PCB
