public class ModbusManager extends ModbusWorker {

    private static volatile ModbusManager sInstance;

    public static ModbusManager get() {
        ModbusManager manager = sInstance;
        if (manager == null) {
            synchronized (ModbusManager.class) {
                manager = sInstance;
                if (manager == null) {
                    manager = new ModbusManager();
                    sInstance = manager;
                }
            }
        }
        return manager;
    }

    private ModbusManager() {
    }

    /**
     * 释放整个ModbusManager，单例会被置null
     */
    public synchronized void release() {
        super.release();
        sInstance = null;
    }
}

ModbusParam serialParam =
    SerialParam.create(devicePath, baudrate).setTimeout(1000).setRetries(0); // 不重试

ModbusManager.get().closeModbusMaster(); // 先关闭一下
ModbusManager.get().init(serialParam, new ModbusCallback<ModbusMaster>() {
    @Override
    public void onSuccess(ModbusMaster modbusMaster) {
        showOneToast("打开成功");
    }

    @Override
    public void onFailure(Throwable tr) {
        showOneToast("打开失败");
    }

    @Override
    public void onFinally() {
        // todo updateDeviceSwitchButton();
    }
});

// 启用rtu的crc校验（默认就启用）
ModbusConfig.setEnableRtuCrc(true);
// 打印数据log（默认全禁用）
// System.out: MessagingControl.send: 01030000000305cb
// System.out: MessagingConnection.read: 010306000100020000bd75
ModbusConfig.setEnableDataLog(true, true);

// 普通写法
ModbusManager.get()
    .readHoldingRegisters(mSalveId, mOffset, mAmount,
        new ModbusCallback<ReadHoldingRegistersResponse>() {
            @Override
            public void onSuccess(
                ReadHoldingRegistersResponse readHoldingRegistersResponse) {
                byte[] data = readHoldingRegistersResponse.getData();
                mTvConsole.append("F03读取：" + ByteUtil.bytes2HexStr(data) + "\n");
            }

            @Override
            public void onFailure(Throwable tr) {
                appendError("F03", tr);
            }

            @Override
            public void onFinally() {

            }
        });

// Rx写法
ModbusManager.get()
    .rxReadHoldingRegisters(mSalveId, mOffset, mAmount)
    .observeOn(AndroidSchedulers.mainThread())
    .compose(this.<ReadHoldingRegistersResponse>bindUntilEvent(ActivityEvent.DESTROY))
    .subscribe(new ModbusObserver<ReadHoldingRegistersResponse>() {
        @Override
        public void onSuccess(
            ReadHoldingRegistersResponse readHoldingRegistersResponse) {
            byte[] data = readHoldingRegistersResponse.getData();
            mTvConsole.append("F03读取：" + ByteUtil.bytes2HexStr(data) + "\n");
        }

        @Override
        public void onFailure(Throwable tr) {
            appendError("F03", tr);
        }
    });