Modbus Message Packets The message packets described below correspond to the Modbus protocol. For more information on Modbus message packets, see the Modbus Protocol Reference available from AEG Schneider Automation. For additional reference on Modbus Guide, message packets, see the which can be Modbus Application Protocol Specification V1.1b found on the website . Function Code 1: Read Coils Request 1 Byte 1 to 255 PLC Node Address 1 Byte 0x01 Function Code 2 Bytes 0x0000 to 0xFFFF Starting Address 2 Bytes 1 to 2000 Quantity of Coils 2 Bytes Variable CRC Response 1 Byte 1 to 255 PLC Node Address 1 Byte 0x01 Function Code 1 Byte N = Quantity of coils / 8 Byte Count N Bytes Value(s) Coil Status 2 Bytes Variable CRC
Modbus Message Packets The message packets described below correspond to the Modbus protocol. For more information on Modbus message packets, see the Modbus Protocol Reference Guide, available from AEG Schneider Automation. For additional reference on Modbus message packets, see the Modbus Application Protocol Specification V1.1b which can be found on the website . Function Code 1: Read Coils Request PLC Node Address 1 Byte 1 to 255 Function Code 1 Byte 0x01 Starting Address 2 Bytes 0x0000 to 0xFFFF Quantity of Coils 2 Bytes 1 to 2000 CRC 2 Bytes Variable Response PLC Node Address 1 Byte 1 to 255 Function Code 1 Byte 0x01 Byte Count 1 Byte N = Quantity of coils / 8 Coil Status N Bytes Value(s) CRC 2 Bytes Variable
PI_ModbusS_4.0.7.61.docx