net.wimpi.modbus.ModbusIOException：I / O异常 - 无法读取

Question

我正在使用串行Modbus（jamod）从设备读取数据。我能够连接到设备但无法从寄存器中读取数据。

这是我的代码：

public class Serial {

    static SerialConnection connection = null;
    SerialParameters params;
    ModbusSerialTransaction transaction = null;

    ReadMultipleRegistersRequest holdingRequest = null;
    ReadMultipleRegistersResponse holdingResponse = null;

    public void getData() {
        try {
            ModbusCoupler.getReference().setUnitID(1);
            params = new SerialParameters();
            params.setPortName("/dev/ttyS0");
            params.setBaudRate(9600);
            params.setDatabits(8);
            params.setEncoding(Modbus.SERIAL_ENCODING_RTU);
            params.setParity("None");
            params.setStopbits(1);
            params.setEcho(false);
            params.setReceiveTimeout(500);
            connection = new SerialConnection(params);
            connection.open();
            checkRegister(40257, 2);
            connection.close();

        } catch(Exception e) {
            e.printStackTrace();
        }
    }

    public void registerData(int address, int count) {
        holdingRequest = new ReadMultipleRegistersRequest(address, count);
        holdingResponse = new ReadMultipleRegistersResponse();
        holdingRequest.setUnitID(130); // I tried with 1 and getting same error
        holdingRequest.setHeadless();
        holdingResponse = (ReadMultipleRegistersResponse) executeRequest(connection, holdingRequest);
        System.out.println("Response: " + holdingResponse);
    }

    private ModbusResponse executeRequest(SerialConnection connection, ModbusRequest request) {
        try {
            transaction = new ModbusSerialTransaction(connection);
            transaction.setRequest(request);
            Thread.sleep(500);
            transaction.execute(); // Error at this line
            return transaction.getResponse();
        } catch(Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}

我在第transaction.execute()行收到以下错误：

net.wimpi.modbus.ModbusIOException: I/O exception - failed to read
    at net.wimpi.modbus.io.ModbusRTUTransport.readResponse(ModbusRTUTransport.java:163)
    at net.wimpi.modbus.io.ModbusSerialTransaction.execute(ModbusSerialTransaction.java:187)
    at Serial.executeRequest(Serial.java:279)
    at Serial.checkRegister(Serial.java:337)
    at Serial.getData(Serial.java:66)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.camel.component.bean.MethodInfo.invoke(MethodInfo.java:408)
    at org.apache.camel.component.bean.MethodInfo$1.doProceed(MethodInfo.java:279)
    at org.apache.camel.component.bean.MethodInfo$1.proceed(MethodInfo.java:252)
    at org.apache.camel.component.bean.BeanProcessor.process(BeanProcessor.java:177)
    at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:77)
    at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:460)
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:190)
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:190)
    at org.apache.camel.component.timer.TimerConsumer.sendTimerExchange(TimerConsumer.java:165)
    at org.apache.camel.component.timer.TimerConsumer$1.run(TimerConsumer.java:73)
    at java.util.TimerThread.mainLoop(Timer.java:555)
    at java.util.TimerThread.run(Timer.java:505)

任何建议都将受到赞赏。