Currently we are disappointed by the dramatic increase of the scan cycle time when using multi-instance FB's and structures (UDT's) for parameter passing. Even with a CPU416-2, processing a single FB takes milliseconds!

With only a fraction of the automation tasks finished, we experience cycle times already over 50ms, which is totally unacceptable!

Does someone have similar experiences or workarounds? Should we forget about these splendid object oriented alike techniques in S7 and program things in the traditional S5 way?

Thanks in advance.
Piet Snoodijk.

 

Hi Piet, I have programmed a series of STEP7 applications using multi istanced FBs and structured-parameters passing. I did not experienced scan cycle problems, my biggest application on a CPU416 runs at max 19mS, and I got no problems using the same techniques on CPU314 / CPU315 PLCs. Obviously if you pass as parameter a huge quantity of data, some delay is expected... but I would search some other reason for such a slow scan time. If you like a detailed discussion, you can contact me privately. >Does someone have similar experiences or workarounds? Should we forget about >these splendid object oriented alike techniques in S7 and program things in >the traditional S5 way? In my opinion, what you call "object oriented alike techniques" , along with CASE capabilities offered by the source compiler, are the most powerful features of S7 and I would never turn back to program an S7 in Step5 way. bye Luca Gallina [email protected]