com.digitalpetri.modbus.server.SerialPortServerTransport Maven / Gradle / Ivy

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package com.digitalpetri.modbus.server;

import com.digitalpetri.modbus.ModbusRtuFrame;
import com.digitalpetri.modbus.ModbusRtuRequestFrameParser;
import com.digitalpetri.modbus.ModbusRtuRequestFrameParser.Accumulated;
import com.digitalpetri.modbus.ModbusRtuRequestFrameParser.ParserState;
import com.digitalpetri.modbus.SerialPortTransportConfig;
import com.digitalpetri.modbus.SerialPortTransportConfig.Builder;
import com.digitalpetri.modbus.exceptions.UnknownUnitIdException;
import com.digitalpetri.modbus.internal.util.ExecutionQueue;
import com.fazecast.jSerialComm.SerialPort;
import com.fazecast.jSerialComm.SerialPortDataListener;
import com.fazecast.jSerialComm.SerialPortEvent;
import java.nio.ByteBuffer;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Consumer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Modbus RTU/Serial server transport; a {@link ModbusRtuServerTransport} that sends and receives
 * {@link ModbusRtuFrame}s over a serial port.
 */
public class SerialPortServerTransport implements ModbusRtuServerTransport {

  private final Logger logger = LoggerFactory.getLogger(getClass());

  private final ModbusRtuRequestFrameParser frameParser = new ModbusRtuRequestFrameParser();
  private final AtomicReference>
      frameReceiver = new AtomicReference<>();

  private final ExecutionQueue executionQueue;

  private final SerialPort serialPort;

  private final SerialPortTransportConfig config;

  public SerialPortServerTransport(SerialPortTransportConfig config) {
    this.config = config;

    serialPort = SerialPort.getCommPort(config.serialPort());

    serialPort.setComPortParameters(
        config.baudRate(),
        config.dataBits(),
        config.stopBits(),
        config.parity(),
        config.rs485Mode()
    );

    executionQueue = new ExecutionQueue(config.executor());
  }

  @Override
  public CompletionStage bind() {
    if (serialPort.isOpen()) {
      return CompletableFuture.completedFuture(null);
    } else {
      if (serialPort.openPort()) {
        frameParser.reset();

        serialPort.addDataListener(new ModbusRtuDataListener());

        return CompletableFuture.completedFuture(null);
      } else {
        return CompletableFuture.failedFuture(
            new Exception(
                "failed to open port '%s', lastErrorCode=%d"
                    .formatted(config.serialPort(), serialPort.getLastErrorCode()))
        );
      }
    }
  }

  @Override
  public CompletionStage unbind() {
    if (serialPort.isOpen()) {
      if (serialPort.closePort()) {
        frameParser.reset();

        return CompletableFuture.completedFuture(null);
      } else {
        return CompletableFuture.failedFuture(
            new Exception(
                "failed to close port '%s', lastErrorCode=%d"
                    .formatted(config.serialPort(), serialPort.getLastErrorCode()))
        );
      }
    } else {
      return CompletableFuture.completedFuture(null);
    }
  }

  @Override
  public void receive(FrameReceiver frameReceiver) {
    this.frameReceiver.set(frameReceiver);
  }

  private class ModbusRtuDataListener implements SerialPortDataListener {

    /**
     * Bit mask indicating what events we're interested in.
     */
    private static final int LISTENING_EVENTS = SerialPort.LISTENING_EVENT_DATA_RECEIVED;

    @Override
    public int getListeningEvents() {
      return LISTENING_EVENTS;
    }

    @Override
    public void serialEvent(SerialPortEvent event) {
      if ((event.getEventType() & LISTENING_EVENTS) == LISTENING_EVENTS) {
        onDataReceived(event);
      }
    }

    private void onDataReceived(SerialPortEvent event) {
      byte[] receivedData = event.getReceivedData();

      ParserState state = frameParser.parse(receivedData);

      if (state instanceof Accumulated a) {
        try {
          onFrameReceived(a.frame());
        } finally {
          frameParser.reset();
        }
      }
    }

    private void onFrameReceived(ModbusRtuFrame requestFrame) {
      FrameReceiver frameReceiver =
          SerialPortServerTransport.this.frameReceiver.get();

      if (frameReceiver != null) {
        executionQueue.submit(() -> {
          try {
            ModbusRtuFrame responseFrame =
                frameReceiver.receive(new ModbusRtuRequestContext() {}, requestFrame);

            int unitId = responseFrame.unitId();
            ByteBuffer pdu = responseFrame.pdu();
            ByteBuffer crc = responseFrame.crc();

            byte[] data = new byte[1 + pdu.remaining() + crc.remaining()];
            data[0] = (byte) unitId;
            pdu.get(data, 1, pdu.remaining());
            crc.get(data, data.length - 2, crc.remaining());

            int totalWritten = 0;
            while (totalWritten < data.length) {
              int written = serialPort.writeBytes(data, data.length - totalWritten, totalWritten);
              if (written == -1) {
                logger.error("Error writing frame to serial port");

                return;
              }
              totalWritten += written;
            }
          } catch (UnknownUnitIdException e) {
            logger.debug("Ignoring request for unknown unit id: {}", requestFrame.unitId());
          } catch (Exception e) {
            logger.error("Error handling frame: {}", e.getMessage(), e);
          }
        });
      }
    }

  }

  /**
   * Create a new {@link SerialPortServerTransport} with a callback that allows customizing the
   * configuration.
   *
   * @param configure a {@link Consumer} that accepts a
   *     {@link SerialPortTransportConfig.Builder} instance to configure.
   * @return a new {@link SerialPortServerTransport}.
   */
  public static SerialPortServerTransport create(
      Consumer configure
  ) {

    var builder = new SerialPortTransportConfig.Builder();
    configure.accept(builder);
    return new SerialPortServerTransport(builder.build());
  }

}