// Creates new ModbusRTU connection
func NewRtuConnection(device string, baud int, parity byte, data_bit uint8, stop_bit uint8) (*RtuConnection, error) {
cs := C.CString(device)
defer C.free(unsafe.Pointer(cs))
context, errno := C.modbus_new_rtu(cs, C.int(baud), C.char(parity), C.int(data_bit), C.int(stop_bit))
if context == nil {
return nil, errors.New(fmt.Sprintf("Failed to create libmodbus context: %s", modbus_strerror(errno)))
}
return &RtuConnection{context, INVALID_SLAVE, false}, nil
}
func NewModbusRTUConnection(DeviceName string,
Speed int, SerialMode string, Hook ioCtlHook) (*ModbusRTUConnection, error) {
// is allready opened?
for _, connection := range ModbusRTUConnections {
if connection.Device() == DeviceName {
if connection.serialMode == SerialMode {
return connection, nil
} else {
return nil, errors.New(
fmt.Sprintf("Device '%s' used by connection %d, mode '%s'",
DeviceName, connection.ID(), connection.serialMode))
}
}
}
result := &ModbusRTUConnection{deviceName: DeviceName, speed: Speed,
serialMode: SerialMode, hook: Hook}
if Hook != nil {
result.rwCtlChan = make(chan int)
go func(oneByteTime time.Duration) {
for v := range result.rwCtlChan {
if v < 0 {
break
}
result.hook.OnStartTransmitting()
time.Sleep(oneByteTime * time.Duration(v))
result.hook.OnEndTransmitting()
}
}(time.Duration(math.Ceil(float64(time.Second*(1+8+0+1)) / float64(result.speed))))
}
// try open
match := parser.FindStringSubmatch(result.serialMode)
if len(match) != (1 + 3) {
result.ctx = C.modbus_new_rtu(C.CString(result.deviceName), C.int(result.speed),
C.char('N'), C.int(8), C.int(1))
} else {
databits, _ := strconv.ParseInt(match[1+0], 10, 32)
stopbits, _ := strconv.ParseInt(match[1+2], 10, 32)
result.ctx = C.modbus_new_rtu(C.CString(result.deviceName), C.int(result.speed),
C.char(match[1+1][0]),
C.int(databits),
C.int(stopbits))
}
if result.ctx == nil {
return nil, errors.New(fmt.Sprintf("Unable to create the libmodbus context\n%s",
C.GoString(C.modbus_strerror(C.getErrno()))))
}
runtime.SetFinalizer(result, finaliserModbusRTUConnection)
result.id = index
index++
if len(ModbusRTUConnections) != 0 &&
ModbusRTUConnections[len(ModbusRTUConnections)-1] == nil {
for i := len(ModbusRTUConnections) - 1; i > -1; i-- {
if ModbusRTUConnections[i] != nil {
ModbusRTUConnections[i+1] = result
break
}
}
} else {
ModbusRTUConnections = append(ModbusRTUConnections, result)
}
return result, nil
}
