Detcon 240 - Manual (Page 22)

240 Operators Manual
Model 240 Operator Manual Rev. 1.8 Page 18 of 29
7.
System Features
7.1 Modbus Communications
The model 240 controller features a Modbus compatible communications protocol and is addressable by a
PLC, PC/HMI, DCS, or other Modbus RTU master polling device. Communications is accomplished by
two wire half duplex RS-485, 9600 baud, 8 data bits, 1 stop bit, no parity, through the controllers secondary
port. Wiring should be brought directly to J10 located on the motherboard.
A Modbus™ RTU master device up to 4000 feet away can theoretically poll up to 64 different controllers.
This number may not be realistic in harsh environments where noise and/or wiring conditions would make
it impractical to place so many devices on the same pair of wires. If a multi-point system is being utilized,
each controller must be set to a different device address.
Modbus™ Register Detail:
Code 03 - Read Holding Registers is the only code supported by the 240 controller.
Register #
40000
Channel 1 Reading
40001 Channel 2 Reading
40002 Fault Status Bits
High Byte
Bit 7
Not Used
Bit 6 Not Used
Bit 5 Not Used
Bit 4 Not Used
Bit 3 Not Used
Bit 2 Not Used
Bit 1 Not Used
Bit 0 Not Used
Low Byte
Bit 7
Not Used
Bit 6 Not Used
Bit 5 Not Used
Bit 4 Not Used
Bit 3 Not Used
Bit 2 Not Used
Bit 1 1 = Channel 2 Fault 0 = Channel 2 no Fault
Bit 0 1 = Channel 1 Fault 0 = Channel 1 no Fault
40003 Alarm 1 Status Bits
High Byte
Bit 7
Not Used
Bit 6 Not Used
Bit 5 Not Used
Bit 4 Not Used
Bit 3 Not Used
Bit 2 Not Used
Bit 1 Not Used
Bit 0 Not Used
Low Byte