Function Code 4: Read Input Registers Request 1 Byte 1 to 255 PLC Node Address 1 Byte 0x04 Function Code 2 Bytes 0x0000 to 0xFFFF Starting Address 2 Bytes 1 to 125 Quantity of Registers 2 Bytes Variable CRC Response 1 Byte 1 to 255 PLC Node Address 1 Byte 0x04 Function Code 1 Byte 2 * N (Quantity of registers) Byte Count N * 2 Bytes Value(s) Holding Registers 2 Bytes Variable CRC Function Code 5: Write Single Coil Request 1 Byte 1 to 255 PLC Node Address 1 Byte 0x05 Function Code 2 Bytes 0x0000 to 0xFFFF Output Address 2 Bytes 0x0000 or 0xFF00 Output Value 2 Bytes Variable CRC Response 1 Byte 1 to 255 PLC Node Address 1 Byte 0x05 Function Code 2 Bytes 0x0000 to 0xFFFF Output Address 2 Bytes 0x0000 or 0xFF00 Output Value 2 Bytes Variable CRC
Function Code 4: Read Input Registers Request PLC Node Address 1 Byte 1 to 255 Function Code 1 Byte 0x04 Starting Address 2 Bytes 0x0000 to 0xFFFF Quantity of Registers 2 Bytes 1 to 125 CRC 2 Bytes Variable Response PLC Node Address 1 Byte 1 to 255 Function Code 1 Byte 0x04 Byte Count 1 Byte 2 * N (Quantity of registers) Holding Registers N * 2 Bytes Value(s) CRC 2 Bytes Variable Function Code 5: Write Single Coil Request PLC Node Address 1 Byte 1 to 255 Function Code 1 Byte 0x05 Output Address 2 Bytes 0x0000 to 0xFFFF Output Value 2 Bytes 0x0000 or 0xFF00 CRC 2 Bytes Variable Response PLC Node Address 1 Byte 1 to 255 Function Code 1 Byte 0x05 Output Address 2 Bytes 0x0000 to 0xFFFF Output Value 2 Bytes 0x0000 or 0xFF00 CRC 2 Bytes Variable
PI_ModbusS_4.0.7.61.docx