8/18/2017 3:46 PM | |
Joined: 9/27/2006 Last visit: 9/22/2024 Posts: 12282 Rating: (2685)
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Hello electrons; Have a look at this very interesting discussion, comments from Hamid Hosseini and fritz should give you things to think about. S7-300, 314 - Entries - Forum - Industry Support - SiemensWe have done a project a few years ago with 25 temperature loops in a S7-313C-3DP, and it was a struggle. If we had to do it again, we would probably go for a CPU 317-2DP or even a CPU 319-2DP, mainly because managing to twist our way around the lack of work memory (using multi-instance FBs and STL code) we still had very little room to consider other control elements of the process. We would have appreciated the legroom. And this was a temperature control project, slow moving... I do not know how fast you can expect your pressure inputs to change, but I suspect that you will need to maintain a very good grip on the analog inputs if you want to have a stable process. Hope this helps, Daniel Chartier |
Last edited by: dchartier at: 8/18/2017 3:53:05 PM |
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This contribution was helpful to2 thankful Users |
9/1/2017 8:35 AM | |
Joined: 1/2/2014 Last visit: 8/16/2024 Posts: 142 Rating: (22) |
We have used 73 PID with 319 CPU, 30 temperature loops and rest with level and pressure. Temp loops called in slower interrupt OB33, with scheduler logic ie only certain loops are taken at one scan. For our application it was Okie. Level controls also scheduled since time response is not much critical for our application. Sampling time |
This contribution was helpful to2 thankful Users |
11/6/2017 1:29 PM | |
Joined: 6/19/2017 Last visit: 9/6/2024 Posts: 8175 Rating: (172) |
New question published by electrons is split to a separate thread with the subject How much the conversion time of Analog input module can influence in PID process?. Best regards |
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