[Bug]: Modbus Rtu/Ascii ping always fail

[dasoops]

What happened?

Execute this code

public class ModbusRtuPingTest {
    @Test
    void testPing() throws Exception {
        var connection = PlcDriverManager.getDefault().getConnectionManager().getConnection("modbus-rtu:tcp://localhost:502");
        Assertions.assertDoesNotThrow(() -> connection.ping().join());
    }
}

Then

org.opentest4j.AssertionFailedError: Unexpected exception thrown: java.lang.NullPointerException: Cannot invoke "Object.getClass()" because "tag" is null

	at org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:152)
	at org.junit.jupiter.api.AssertDoesNotThrow.createAssertionFailedError(AssertDoesNotThrow.java:84)
	at org.junit.jupiter.api.AssertDoesNotThrow.assertDoesNotThrow(AssertDoesNotThrow.java:75)
	at org.junit.jupiter.api.AssertDoesNotThrow.assertDoesNotThrow(AssertDoesNotThrow.java:58)
	at org.junit.jupiter.api.Assertions.assertDoesNotThrow(Assertions.java:3228)
	at org.apache.plc4x.java.modbus.rtu.ModbusRtuPingTest.testPing(ModbusRtuPingTest.java:30)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1597)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1597)
Caused by: java.lang.NullPointerException: Cannot invoke "Object.getClass()" because "tag" is null
	at org.apache.plc4x.java.modbus.base.protocol.ModbusProtocolLogic.getReadRequestPdu(ModbusProtocolLogic.java:149)
	at org.apache.plc4x.java.modbus.rtu.protocol.ModbusRtuProtocolLogic.ping(ModbusRtuProtocolLogic.java:68)
	at org.apache.plc4x.java.spi.connection.AbstractPlcConnection.ping(AbstractPlcConnection.java:183)
	at org.apache.plc4x.java.spi.messages.DefaultPlcPingRequest.execute(DefaultPlcPingRequest.java:40)
	at org.apache.plc4x.java.spi.connection.DefaultNettyPlcConnection.ping(DefaultNettyPlcConnection.java:205)
	at org.apache.plc4x.java.modbus.rtu.ModbusRtuPingTest.lambda$0(ModbusRtuPingTest.java:30)
	at org.junit.jupiter.api.AssertDoesNotThrow.assertDoesNotThrow(AssertDoesNotThrow.java:71)
	... 6 more

The pingAddress attribute of ModbusRtuProtocolLogic seems to have never been assigned, which is different from ModbusTcpProtocolLogic.

plc4x/plc4j/drivers/modbus/src/main/java/org/apache/plc4x/java/modbus/rtu/protocol/ModbusRtuProtocolLogic.java

Lines 48 to 54 in b186437

	@Override
	public void setConfiguration(ModbusRtuConfiguration configuration) {
	this.requestTimeout = Duration.ofMillis(configuration.getRequestTimeout());
	this.unitIdentifier = (short) configuration.getDefaultUnitIdentifier();
	this.defaultPayloadByteOrder = configuration.getDefaultPayloadByteOrder();
	this.tm = new RequestTransactionManager(1);
	}

Furthermore, its ModbusRtuProtocolLogic.ping() and ModbusRtuDriver.canPing() are both overridden, so I think this is unexpected.

plc4x/plc4j/drivers/modbus/src/main/java/org/apache/plc4x/java/modbus/rtu/protocol/ModbusRtuProtocolLogic.java

Lines 61 to 63 in b186437

	@Override
	public CompletableFuture<PlcPingResponse> ping(PlcPingRequest pingRequest) {
	CompletableFuture<PlcPingResponse> future = new CompletableFuture<>();

plc4x/plc4j/drivers/modbus/src/main/java/org/apache/plc4x/java/modbus/rtu/ModbusRtuDriver.java

Lines 100 to 103 in b186437

	@Override
	protected boolean canPing() {
	return true;
	}

Additionally, ModbusAsciiProtocolLogic also seems to have this issue.

Version

v0.12.0, v0.13.0-SNAPSHOT

Programming Languages

• plc4j
• plc4go
• plc4c
• plc4net

Protocols

• AB-Ethernet
• ADS /AMS
• BACnet/IP
• CANopen
• DeltaV
• DF1
• EtherNet/IP
• Firmata
• KNXnet/IP
• Modbus
• OPC-UA
• S7