Super Systems AC20 RS485 Modbus - Manual (Page 8)

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TITLE: MODBUS/J-BUS Protocol for SSi’s- AC20 ENG. 824E REV. 1
Function code 5: Single bit writing
By using this command, the master unit can change the state of one bit of the slave unit.
Command from master to slave Reply from slave to master
Range Byte Range Byte
Slave address (0*-255) 1 Slave address (1-255) 1
Function code (05) 1 Function code (05) 1
Bit address (high byte) 1 Bit address (high byte) 1
Bit address (low byte) 1 Bit address (low byte) 1
Data 2 Data 2
Error check (CRC-16) (low byte) 1 Error check (CRC-16) (low byte) 1
Error check (CRC-16) (high byte) 1 Error check (CRC-16) (high byte) 1
* To use the address 0, see note 1 at page 12: “Broadcast address”.
“Data” field = 0h to reset the bit
= FF00h to set the bit
Example:
Set bit 219 (DBh) of slave at address 35 (23h)
Command from master to slave Reply from slave to master
Range Byte Range Byte
Slave address 23h Slave address 23h
Function code 05h Function code 05h
Bit address (high byte) 00h Bit address (high byte) 00h
Bit address (low byte) DBh Bit address (low byte) DBh
Data FFh Data FFh
Data 00h Data 00h
Error check (CRC-16) (low byte) FAh Error check (CRC-16) (low byte) FAh
Error check (CRC-16) (high byte) 83h Error check (CRC-16) (high byte) 83h