Modbus TCP with AG_SEND/AG_RCV - S7-315-2DP + CP343-1

Hi guys!

Anyone here who has done modbus TCP communication straight up with AG_SEND and AG_RCV?

Any snags one should know about?

I've done some testing and after setting up a connection I tried sending a modbus request and it worked as expected.

Thanks,
Pete

BTW, I have the "open modbus tcp"-package from Siemens but it seems inflexible and unrefined to me. It also forces me to restart the cpu to set the initialization call in OB100 as well as doing it again for licensing and every time in the future I need to change what areas I need to read or any other configuration of the software. The PLC is running some plant critical stuff so every restart must planned and synchronized and it takes hours.

The "official" modbus TCP implementation is probably implemented using those same blocks. I try to stay away from them whenever I can, you only need to use them for older CPUs. However, if you need to make it work with what you have, it sounds like you already have it working. Whats your question? Are you worried about Modbus TCP implementation or the AGsend/rcv blocks themselves?

btw, in the newer 1500 family, the modbus TCP blocks that are built in require no licensing and are much more flexible. Its a shame they never backported that to the 300 to simplify things.