[Feature Request]: better error message when data-content doesn't mach data-spec in S7

[DvonHolten]

What would you like to happen?

recently i implemented plc communication using S7 put/get-protocol. After some fumbling the adress syntax was correct and reading/writing worked. Then i needed to write value 0x8000 into an "%DB123.DBW96:INT", which failed. Lengthy probing revealed, that 0x8000 is not an Integer in S7, so that WORD format needs to be used instead of INT.
I ask for better error message when communication detects this. All we have now is some NPE when accessing the result-status.

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

[chrisdutz]

Well ... I think we really should remove the option to pass in raw values to write operations. The ideal way would be to pass in a PlcValue. This would have fired an error the moment you tried to create it. The other way just contains way too much potential for things going wrong.

        PlcValue val = new PlcINT(0x8000);
        System.out.println(val);

This results in:

org.apache.plc4x.java.api.exceptions.PlcInvalidTagException: Value of type 32768 is out of range -32768 - 32767 for a PlcINT Value invalid

	at com.toddysoft.connect.java.spi.values.PlcINT.<init>(PlcINT.java:87)
	at com.toddysoft.connect.java.s7.tags.S7TagTest.testDataBlockShortPattern_NonBoolTypeWithBitOffset_ShouldError(S7TagTest.java:526)
	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)

(Ignore the different package ... I just tested that in my commercial offering)

[chrisdutz]

And another option would have been to use an "UINT"