I'm trying to make sense of a reply from a PLC by decoding each Hex value (hint, it's not working lol). It works great with serial MODBUS but TCP/IP is a completely different structure.
Here's what we are seeing. I can't decide if we are getting two RX for every TX or if the event log is just splitting the response into two different lines to make it easier to view. Actually I can decide and that's what I think is going on.
7/20/2022 12:22:56.194 PM TX 60 70 00 24 00 04 00 1C 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 02 00 A1 00 04 00 89 4C 92 FF B1 00 10 00 EA 0B 03 03 20 6B 25 00 BD C6 02 00 03 00 06 00
7/20/2022 12:22:56.237 PM RX 24 70 00 2C 00 04 00 1C 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
7/20/2022 12:22:56.237 PM RX 44 00 00 00 00 00 00 02 00 A1 00 04 00 01 00 FE 80 B1 00 18 00 EA 0B 83 00 00 00 02 00 03 00 00 00 84 1D 08 00 06 00 00 00 8A 44 01 0C
The next thing to try was to make a spreadsheet, use HEX2DEC to convert each Hex value to decimal. Like magic I expected (not really) to see the IP address of the PLC in the data. The problem is, if I understand TCP/IP packet structure right (Vegas odds on that one) the structure isn't as neat and orderly as that.
Rather than continue telling you what I don't know lets go with - Can anyone here decode this?