4/28/2016 10:16 AM | |
Joined: 5/28/2008 Last visit: 4/15/2024 Posts: 4505 Rating: (835)
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Hello, If access is made to the inputs and outputs via the operands "I..." or "Q..." in the user program, then there is no direct access to the input/output modules. In this case, access is made to a memory area in the CPU's system memory. This area is called the process image of the inputs (PII) and the process image of the outputs (PIQ). The contents of the process image (PII and PIQ) do not reflect the actual values of the inputs/outputs, but the values at the time the process image was updated. If more recent values are required for individual processes, you also have the option of direct peripheral addressing. Please see this important link And also this one Hope this helps. |
Ayman Elotaify |
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4/28/2016 10:26 AM | |
Posts: 223 Rating: (0) |
But when do you reach the limit of DI / AI-modules? |
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4/28/2016 10:37 AM | |
Joined: 3/5/2014 Last visit: 8/5/2022 Posts: 5521 Rating: (1050) |
hi ToVerm this depends on adress-range of CPU and with ET200s, have a look to the System-Manual: SIMATIC Distributed I/O System ET 200S
hope this helps, regards |
FCK WAR! |
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4/28/2016 10:51 AM | |
Joined: 7/2/2008 Last visit: 4/5/2024 Posts: 928 Rating: (305) |
Hello ToVerm, You can also check address gaps in HW configuration. Check attachment. Best regards, H-H AttachmentAddress gaps.pdf (59 Downloads) |
4/28/2016 11:01 AM | |
Posts: 223 Rating: (0) |
OK, I think I got it already. In the adress overview I can see that not all the adresses are used. So I can arrange the adresses of the ET200S-modules so that it fits in between the other (already assigned) adresses. So I think that it will work. Also I can install 14 extra decentral I/O-modules into the system. So there shouldn't be a problem. |
4/28/2016 11:38 AM | |
Joined: 5/28/2008 Last visit: 4/15/2024 Posts: 4505 Rating: (835)
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Hello, And another important note you should take into consideration. When let the CPU read or write out side PII/or PIQ using peripheral addressing it takes time grater than if it will read the input without using peripheral addressing. And the differnce can not be neglegted. |
Ayman Elotaify |
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4/28/2016 2:40 PM | |
Posts: 223 Rating: (0) |
That won't be a problem either. Most inputs will be in the process image input area. |
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