0x41

client.go

@@ -1188,15 +1188,9 @@ func (mc *ModbusClient) readRegistersWithFunctionCode(addr uint16, quantity uint
 		unitId: mc.unitId,
 	}
 
-	// if functionCode != fcCustomize {
+	if functionCode != fcCustomize {
-	// 	err = ErrUnexpectedParameters
-	// 	mc.logger.Errorf("unexpected function code (%d)", functionCode)
-	// 	return
-	// }
-
-	if functionCode == 0 {
 		err = ErrUnexpectedParameters
-		mc.logger.Errorf("unexpected register type (%v)", functionCode)
+		mc.logger.Errorf("unexpected function code (%d)", functionCode)
 		return
 	}
 
@@ -1208,7 +1202,8 @@ func (mc *ModbusClient) readRegistersWithFunctionCode(addr uint16, quantity uint
 		return
 	}
 
-	if quantity > 1024 {
+	// 16 * 16 * 40
+	if quantity > 10240 {
 		err = ErrUnexpectedParameters
 		mc.logger.Error("quantity of registers exceeds 1024")
 		return

modbus.go

@@ -41,7 +41,7 @@ const (
 	fcWriteFileRecord uint8 = 0x15
 
 	// customize
-	fcCustomize uint8 = 0x29
+	fcCustomize uint8 = 0x41
 
 	// exception codes
 	exIllegalFunction         uint8 = 0x01

rtu_transport.go

@@ -21,10 +21,10 @@ type rtuTransport struct {
 }
 
 type rtuLink interface {
-	Close()		(error)
+	Close() error
 	Read([]byte) (int, error)
 	Write([]byte) (int, error)
-	SetDeadline(time.Time)	(error)
+	SetDeadline(time.Time) error
 }
 
 // Returns a new RTU transport.
@@ -140,7 +140,7 @@ func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) {
 	var bytesNeeded int
 	var crc crc
 
-	rxbuf		= make([]byte, maxRTUFrameLength)
+	rxbuf = make([]byte, 10243)
 
 	// read the serial ADU header: unit id (1 byte), function code (1 byte) and
 	// PDU length/exception code (1 byte)
@@ -163,12 +163,12 @@ func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) {
 	bytesNeeded += 2
 
 	// never read more than the max allowed frame length
-	if byteCount + bytesNeeded > maxRTUFrameLength {
+	if byteCount+bytesNeeded > maxRTUFrameLength {
 		err = ErrProtocolError
 		return
 	}
 
-	byteCount, err	= io.ReadFull(rt.link, rxbuf[3:3 + bytesNeeded])
+	byteCount, err = io.ReadFull(rt.link, rxbuf[3:3+bytesNeeded])
 	if err != nil && err != io.ErrUnexpectedEOF {
 		return
 	}
@@ -180,10 +180,10 @@ func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) {
 
 	// compute the CRC on the entire frame, excluding the CRC
 	crc.init()
-	crc.add(rxbuf[0:3 + bytesNeeded - 2])
+	crc.add(rxbuf[0 : 3+bytesNeeded-2])
 
 	// compare CRC values
-	if !crc.isEqual(rxbuf[3 + bytesNeeded - 2], rxbuf[3 + bytesNeeded - 1]) {
+	if !crc.isEqual(rxbuf[3+bytesNeeded-2], rxbuf[3+bytesNeeded-1]) {
 		err = ErrBadCRC
 		return
 	}
@@ -192,7 +192,7 @@ func (rt *rtuTransport) readRTUFrame() (res *pdu, err error) {
 		unitId:       rxbuf[0],
 		functionCode: rxbuf[1],
 		// pass the byte count + trailing data as payload, withtout the CRC
-		payload:	rxbuf[2:3 + bytesNeeded  - 2],
+		payload: rxbuf[2 : 3+bytesNeeded-2],
 	}
 
 	return
@@ -222,12 +222,16 @@ func expectedResponseLenth(responseCode uint8, responseLength uint8) (byteCount
 	case fcReadHoldingRegisters,
 		fcReadInputRegisters,
 		fcReadCoils,
-	     fcReadDiscreteInputs:            byteCount = int(responseLength)
+		fcReadDiscreteInputs,
+		0x41:
+		byteCount = int(responseLength)
 	case fcWriteSingleRegister,
 		fcWriteMultipleRegisters,
 		fcWriteSingleCoil,
-	     fcWriteMultipleCoils:            byteCount = 3
+		fcWriteMultipleCoils:
-	case fcMaskWriteRegister:             byteCount = 5
+		byteCount = 3
+	case fcMaskWriteRegister:
+		byteCount = 5
 	case fcReadHoldingRegisters | 0x80,
 		fcReadInputRegisters | 0x80,
 		fcReadCoils | 0x80,
@@ -236,8 +240,11 @@ func expectedResponseLenth(responseCode uint8, responseLength uint8) (byteCount
 		fcWriteMultipleRegisters | 0x80,
 		fcWriteSingleCoil | 0x80,
 		fcWriteMultipleCoils | 0x80,
-	     fcMaskWriteRegister | 0x80:      byteCount = 0
+		fcMaskWriteRegister | 0x80,
-	default: err = ErrProtocolError
+		0x41 | 0x80:
+		byteCount = 0
+	default:
+		err = ErrProtocolError
 	}
 
 	return