Set read deadline correctly

client.go

@@ -17,10 +17,11 @@ type Mbclient struct {
 	conn               net.Conn
 	t                  *time.Timer
 	keepAliveDuration  time.Duration
+	timeOut            time.Duration
 	wg                 sync.WaitGroup
 }
 
-func New(Address string, Unit uint8, KeepAlive time.Duration) (*Mbclient, error) {
+func New(Address string, Unit uint8, KeepAlive, TimeOut time.Duration) (*Mbclient, error) {
 
 	c := new(Mbclient)
 	c.address = Address
@@ -28,6 +29,7 @@ func New(Address string, Unit uint8, KeepAlive time.Duration) (*Mbclient, error)
 	c.t = time.NewTimer(0)
 	<-c.t.C
 	c.keepAliveDuration = KeepAlive
+	c.timeOut = TimeOut
 	return c, nil
 }
 
@@ -54,7 +56,7 @@ func (m *Mbclient) ReadRegisters(first uint16, numRegs uint16) ([]uint16, error)
 		// 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, 5*time.Second)
+		m.conn, err = net.DialTimeout("tcp", m.address, m.timeOut)
 		if err != nil {
 			return nil, err
 		}
@@ -76,6 +78,7 @@ func (m *Mbclient) ReadRegisters(first uint16, numRegs uint16) ([]uint16, error)
 	binary.BigEndian.PutUint16(req[8:10], first-1)
 	binary.BigEndian.PutUint16(req[10:12], numRegs)
 	m.conn.SetDeadline(time.Now().Add(5 * time.Second))
+
 	byteswritten, err := m.conn.Write(req)
 	if err != nil {
 		m.closeConn()
@@ -85,7 +88,7 @@ func (m *Mbclient) ReadRegisters(first uint16, numRegs uint16) ([]uint16, error)
 		m.closeConn()
 		return nil, fmt.Errorf("failed to send request")
 	}
-	m.conn.SetDeadline(time.Now().Add(5 * time.Second))
+	m.conn.SetDeadline(time.Now().Add(m.timeOut))
 	_, err = io.ReadFull(m.conn, m.header[:])
 	if err != nil {
 		m.closeConn()
@@ -95,10 +98,11 @@ func (m *Mbclient) ReadRegisters(first uint16, numRegs uint16) ([]uint16, error)
 	expectedDataLength := responseHeader.length - 1
 
 	if m.transactionCounter != responseHeader.transactionID {
-		m.t.Reset(0)
+		m.closeConn()
 		return nil, fmt.Errorf("modbus transaction mismatch %v != %v", m.transactionCounter, responseHeader.transactionID)
 	}
 	response := make([]byte, expectedDataLength)
+	m.conn.SetDeadline(time.Now().Add(m.timeOut))
 	bytesRead, err := io.ReadFull(m.conn, response)
 	if err != nil {
 		m.closeConn()
@@ -112,7 +116,7 @@ func (m *Mbclient) ReadRegisters(first uint16, numRegs uint16) ([]uint16, error)
 	err = mbpayload.unMarshal(response)
 	if mbpayload.functionCode != 3 {
 		m.t.Reset(m.keepAliveDuration)
-		return nil, fmt.Errorf("modbus exception %v req: %v", mbpayload.functionCode&0x7F, req)
+		return nil, fmt.Errorf("modbus exception %v req: %x", mbpayload.functionCode&0x7F, req)
 	}
 	if err != nil {
 		m.t.Reset(m.keepAliveDuration)

client_test.go

@@ -8,7 +8,7 @@ import (
 )
 
 func TestReadOneRegisterKeepAlive(t *testing.T) {
-	c, err := New("IAM_248000012514.solver.nu:502", 1, 100*time.Millisecond)
+	c, err := New("IAM_248000012514.solver.nu:502", 1, 100*time.Millisecond, 5*time.Second)
 	t.Log("Connect")
 	assert.NoError(t, err)
 	for n := 0; n < 5; n++ {
@@ -36,7 +36,7 @@ func TestReadOneRegisterKeepAlive(t *testing.T) {
 }
 
 func TestReadOneRegisterShortKeepAlive(t *testing.T) {
-	c, err := New("IAM_248000012514.solver.nu:502", 1, 10*time.Nanosecond)
+	c, err := New("IAM_248000012514.solver.nu:502", 1, 10*time.Nanosecond, 5*time.Second)
 	t.Log("Connect")
 	assert.NoError(t, err)
 	for n := 0; n < 5; n++ {
@@ -68,7 +68,7 @@ func TestReadOneRegisterShortKeepAlive(t *testing.T) {
 }
 
 func TestReadALot(t *testing.T) {
-	c, err := New("IAM_248000012514.solver.nu:502", 1, 100*time.Millisecond)
+	c, err := New("IAM_248000012514.solver.nu:502", 1, 100*time.Millisecond, 5*time.Second)
 	t.Log("Connect")
 	assert.NoError(t, err)
 	for n := 0; n < 500; n++ {