writeSingleCoil method

@override Future<void> writeSingleCoil(int slaveId, int address, bool isOn)

Write single coil (FC 05).

Writes a single coil to either ON or OFF.

Parameters:

• slaveId: The slave device ID (0-247, 0 for broadcast)
• address: Coil address
• isOn: true for ON (0xFF00), false for OFF (0x0000)

Example:

await client.writeSingleCoil(1, 0, true); // Turn on coil 0

Implementation

@override
Future<void> writeSingleCoil(int slaveId, int address, bool isOn) async {
  if (slaveId > _addressMax) {
    throw ArgumentError(
        'modbus: slaveId \'$slaveId\' must be between \'$addressBroadCast\' and \'$_addressMax\'');
  }

  final value = isOn ? 0xFF00 : 0x0000;
  final response = await send(
    slaveId,
    ProtocolDataUnit(
      funcCodeWriteSingleCoil,
      uint16ToBytes([address, value]),
    ),
  );

  if (response.data.length != 4) {
    throw Exception(
        'modbus: response data size \'${response.data.length}\' does not match expected \'4\'');
  }

  final rspAddress = bytesToUint16(response.data.sublist(0, 2))[0];
  if (rspAddress != address) {
    throw Exception(
        'modbus: response address \'$rspAddress\' does not match request \'$address\'');
  }

  final rspValue = bytesToUint16(response.data.sublist(2, 4))[0];
  if (rspValue != value) {
    throw Exception(
        'modbus: response value \'$rspValue\' does not match request \'$value\'');
  }
}