Add tests

When the client got a IO timeout the timer were never reset
Adjusting timeouts

client.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"sync"
 	"time"
 )
 
@@ -13,23 +14,67 @@ type Mbclient struct {
 	address            string
 	header             [7]byte
 	unit               uint8
+	conn               net.Conn
+	t                  *time.Timer
+	keepAliveDuration  time.Duration
+	timeOut            time.Duration
+	wg                 sync.WaitGroup
+	registerOffset     uint16
 }
 
-func New(address string, unit uint8) (*Mbclient, error) {
+func New(Address string, Unit uint8, KeepAlive, TimeOut time.Duration, registerOffset uint16) (*Mbclient, error) {
 
 	c := new(Mbclient)
-	c.address = address
-	c.unit = unit
+	c.address = Address
+	c.unit = Unit
+	c.t = time.NewTimer(0)
+	<-c.t.C
+	c.keepAliveDuration = KeepAlive
+	c.timeOut = TimeOut
+	c.registerOffset = registerOffset
 	return c, nil
 }
 
-func (m *Mbclient) ReadRegisters(first uint16, numRegs uint16) ([]uint16, error) {
+func (m *Mbclient) closer() {
 
-	conn, err := net.Dial("tcp", m.address)
-	if err != nil {
-		return nil, err
+	<-m.t.C
+	m.conn.Close()
+	//m.transactionCounter = 0
+	m.wg.Done()
+}
+
+// closeConn can be called when a tcp communication failure require the current
+// connection to be closed, it should only be used when closer routine is running
+// and the timer is stopped.
+func (m *Mbclient) closeConn() {
+	m.t.Reset(0)
+	m.wg.Wait()
+}
+
+// Reads one or many holding registers (Function code 03)
+func (m *Mbclient) ReadHoldingRegisters(first uint16, numRegs uint16) ([]uint16, error) {
+	return m.readRegisters(3, first, numRegs)
+}
+
+// Reads one or many input registers (Function code 04)
+func (m *Mbclient) ReadInputRegisters(first uint16, numRegs uint16) ([]uint16, error) {
+	return m.readRegisters(4, first, numRegs)
+}
+
+func (m *Mbclient) readRegisters(functionCode uint8, first uint16, numRegs uint16) ([]uint16, error) {
+	var err error
+	// If The timer is expired, conn is closed and needs to be reopened
+	if !m.t.Stop() {
+		// Wait for closer to exit to mitigate race condiion
+		// between closer routine and this code path
+		m.wg.Wait()
+		m.conn, err = net.DialTimeout("tcp", m.address, m.timeOut)
+		if err != nil {
+			return nil, err
+		}
+		m.wg.Add(1)
+		go m.closer()
 	}
-	defer conn.Close()
 
 	const requestLength = 12
 	m.transactionCounter++
@@ -38,36 +83,59 @@ func (m *Mbclient) ReadRegisters(first uint16, numRegs uint16) ([]uint16, error)
 	var mbpayload mbPDU
 
 	binary.BigEndian.PutUint16(req[0:2], m.transactionCounter)
-	binary.BigEndian.PutUint16(req[2:4], 0)
+	binary.BigEndian.PutUint16(req[2:4], 0) // Protocol identifier
 	binary.BigEndian.PutUint16(req[4:6], 6) // Length
 	req[6] = m.unit
-	req[7] = 3 //FunctionCode
-	binary.BigEndian.PutUint16(req[8:10], first-1)
+	req[7] = functionCode
+	binary.BigEndian.PutUint16(req[8:10], first-m.registerOffset)
 	binary.BigEndian.PutUint16(req[10:12], numRegs)
-	conn.SetDeadline(time.Now().Add(10 * time.Second))
-	byteswritten, err := conn.Write(req)
+	m.conn.SetDeadline(time.Now().Add(5 * time.Second))
+
+	byteswritten, err := m.conn.Write(req)
 	if err != nil {
+		m.closeConn()
 		return nil, err
 	}
 	if byteswritten != requestLength {
-		return nil, fmt.Errorf("Failed to send request")
+		m.closeConn()
+		return nil, fmt.Errorf("failed to send request")
+	}
+	m.conn.SetDeadline(time.Now().Add(m.timeOut))
+	_, err = io.ReadFull(m.conn, m.header[:])
+	if err != nil {
+		m.closeConn()
+		return nil, err
 	}
-	conn.SetDeadline(time.Now().Add(10 * time.Second))
-	_, err = io.ReadFull(conn, m.header[:])
 	responseHeader.unMarshal(m.header)
 	expectedDataLength := responseHeader.length - 1
 
+	if m.transactionCounter != responseHeader.transactionID {
+		m.closeConn()
+		return nil, fmt.Errorf("modbus transaction mismatch %v != %v", m.transactionCounter, responseHeader.transactionID)
+	}
 	response := make([]byte, expectedDataLength)
-	_, err = conn.Read(response)
+	m.conn.SetDeadline(time.Now().Add(m.timeOut))
+	bytesRead, err := io.ReadFull(m.conn, response)
+	if err != nil {
+		m.closeConn()
+		return nil, err
+	}
+	if uint16(bytesRead) != expectedDataLength {
+		m.t.Reset(m.keepAliveDuration)
+		return nil, fmt.Errorf("failed to read complete package")
+	}
 
 	err = mbpayload.unMarshal(response)
-	if mbpayload.functionCode != 3 {
-		return nil, fmt.Errorf("modbus exception %v", mbpayload.functionCode&0x7F)
+	if mbpayload.functionCode != functionCode {
+		m.t.Reset(m.keepAliveDuration)
+		return nil, fmt.Errorf("modbus exception %v req: %x", mbpayload.functionCode&0x7F, req)
 	}
 	if err != nil {
+		m.t.Reset(m.keepAliveDuration)
 		return nil, err
 	}
 
+	m.t.Reset(m.keepAliveDuration)
 	return mbpayload.registers, nil
 }
 
@@ -78,10 +146,6 @@ type mbapHeader struct {
 	unitIdentifier     byte
 }
 
-// func (m *mbapHeader) marshalBinary() ([]byte, error) {
-
-// }
-
 func (m *mbapHeader) unMarshal(data [7]byte) error {
 	m.transactionID = binary.BigEndian.Uint16(data[0:2])
 	m.protocolIdentifier = binary.BigEndian.Uint16(data[2:4])
@@ -101,7 +165,7 @@ func (d *mbPDU) unMarshal(data []byte) error {
 	d.functionCode = data[0]
 	d.length = data[1]
 	if d.length+2 != uint8(len(data)) {
-		return fmt.Errorf("Lenght mismatch in modbus payload")
+		return fmt.Errorf("length mismatch in modbus payload")
 	}
 	d.registers = make([]uint16, d.length/2)
 	var n uint8

client_test.go

@@ -2,33 +2,161 @@ package modbustcpclient
 
 import (
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 )
 
-func TestReadOneRegister(t *testing.T) {
-	c, err := New("192.168.0.154:502", 1)
+const testNibeHost = "NIBE-06543922346009.solver.nu:502"
+const testIAMhost = "IAM_248000012514.solver.nu:502"
+
+func TestNibeInputRegsters(t *testing.T) {
+	inputRegs := []uint16{1, 5, 7 /*8,*/, 9, 10, 11, 12, 13, 14, 16 /*26,*/ /*39,*/, 86, 1046, 1083, 1100, 1102, 1104, // S1155 specific
+		40 /*46, 48, 50*/ /* 396, 398,*/, 1017 /*1567,*/, 1025, 1028, 1029, 1083, 1087, 1575, 1577 /*1581,*/, 1583, 1585, 1975} // common registers
+	c, err := New(testNibeHost, 1, 100*time.Millisecond, 5*time.Second, 0)
+	t.Log("Connect")
+	assert.NoError(t, err)
+	for _, reg := range inputRegs {
+
+		res, err := c.ReadInputRegisters(uint16(reg), 1)
+		assert.NoError(t, err, "Failed to read reg %v", reg)
+
+		if err == nil {
+			t.Logf("reg: %v res: %v \n", reg, res)
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+
+	time.Sleep(1 * time.Second)
+}
+
+func TestNibeHoldingRegsters(t *testing.T) {
+	holdingRegs := []uint16{18, 20, 22, 26, 30, 34, 38, 39, 40, 41, 45, 43, 44, 45, 56 /*97, 159,*/, 196, 197, 237}
+	c, err := New(testNibeHost, 1, 100*time.Millisecond, 5*time.Second, 0)
+	t.Log("Connect")
+	assert.NoError(t, err)
+	for _, reg := range holdingRegs {
+
+		res, err := c.ReadHoldingRegisters(uint16(reg), 1)
+		assert.NoError(t, err, "Failed to read reg %v", reg)
+
+		if err == nil {
+			t.Logf("reg: %v res: %v \n", reg, res)
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+
+	time.Sleep(1 * time.Second)
+}
+
+func TestNibeReads32Register(t *testing.T) {
+	holdingRegs := []uint16{1083}
+	c, err := New(testNibeHost, 1, 100*time.Millisecond, 5*time.Second, 0)
+	t.Log("Connect")
+	assert.NoError(t, err)
+	for _, reg := range holdingRegs {
+
+		res, err := c.ReadInputRegisters(uint16(reg), 2)
+		assert.NoError(t, err, "Failed to read reg %v", reg)
+
+		if err == nil {
+			t.Logf("reg: %v res: %v \n", reg, res)
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+}
+
+func TestNibeReadu32ScaledRegister(t *testing.T) {
+	holdingRegs := []uint16{1583}
+	c, err := New(testNibeHost, 1, 100*time.Millisecond, 5*time.Second, 0)
+	t.Log("Connect")
+	assert.NoError(t, err)
+	for _, reg := range holdingRegs {
+
+		res, err := c.ReadInputRegisters(uint16(reg), 2)
+		assert.NoError(t, err, "Failed to read reg %v", reg)
+
+		if err == nil {
+			t.Logf("reg: %v res: %v \n", reg, res)
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+}
+
+func TestReadOneRegisterKeepAlive(t *testing.T) {
+	c, err := New(testIAMhost, 1, 100*time.Millisecond, 5*time.Second, 1)
+	t.Log("Connect")
 	assert.NoError(t, err)
 	for n := 0; n < 5; n++ {
-		res, err := c.ReadRegisters(12401, 2)
+		res, err := c.ReadHoldingRegisters(12401, 2)
 		assert.NoError(t, err)
 		assert.Len(t, res, 2)
 		t.Log(res)
 
-		res, err = c.ReadRegisters(12102, 2)
+		res, err = c.ReadHoldingRegisters(12102, 2)
 		assert.NoError(t, err)
 		assert.Len(t, res, 2)
 		t.Log(res)
 
-		res, err = c.ReadRegisters(12544, 1)
+	}
+	time.Sleep(1 * time.Second)
+}
+
+func TestReadOneRegisterShortKeepAlive(t *testing.T) {
+	c, err := New(testIAMhost, 1, 10*time.Nanosecond, 5*time.Second, 1)
+	t.Log("Connect")
+	assert.NoError(t, err)
+	for n := 0; n < 5; n++ {
+		res, err := c.ReadHoldingRegisters(12401, 2)
+		assert.NoError(t, err)
+		assert.Len(t, res, 2)
+		t.Log(res)
+		time.Sleep(100 * time.Millisecond)
+
+		res, err = c.ReadHoldingRegisters(12102, 2)
+		assert.NoError(t, err)
+		assert.Len(t, res, 2)
+		t.Log(res)
+		time.Sleep(100 * time.Millisecond)
+
+		res, err = c.ReadHoldingRegisters(12544, 1)
 		assert.NoError(t, err)
 		assert.Len(t, res, 1)
 		t.Log(float32(res[0]) / 10)
+		time.Sleep(100 * time.Millisecond)
 
-		res, err = c.ReadRegisters(12136, 1)
+		res, err = c.ReadHoldingRegisters(12136, 1)
 		assert.NoError(t, err)
 		assert.Len(t, res, 1)
 		t.Log(res)
+		time.Sleep(100 * time.Millisecond)
 	}
-
+	time.Sleep(1 * time.Second)
+}
+
+func TestReadALot(t *testing.T) {
+	c, err := New(testIAMhost, 1, 100*time.Millisecond, 5*time.Second, 1)
+	t.Log("Connect")
+	assert.NoError(t, err)
+	for n := 0; n < 500; n++ {
+		t.Log(n)
+		_, err := c.ReadHoldingRegisters(12401, 2)
+		if err != nil {
+			t.Log(err)
+		}
+		_, err = c.ReadHoldingRegisters(12102, 2)
+		if err != nil {
+			t.Log(err)
+		}
+
+		_, err = c.ReadHoldingRegisters(12544, 1)
+		if err != nil {
+			t.Log(err)
+		}
+		_, err = c.ReadHoldingRegisters(12136, 1)
+		if err != nil {
+			t.Log(err)
+		}
+	}
+	time.Sleep(200 * time.Millisecond)
 }