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hanky

CPU usage SoftPLC

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I'm new here, but not new in the Automation business. Problem: I'm working with a Siemens SoftPLC (WinLC). Our CPU usage of the SoftPLC's increases to an excesive high level (>=90%). This is the reason why we sometimes lose data which is supposed to be transferred via OPC. Additional info: I have limited the perpetrator (program which uses the biggest amount of CPU usage) to the WinLC executable (S7wlcvmx.exe). This program is responsible for aprox. 80%. Somehow this executable performs a task which is leading excessive high CPU usage. Nothing special is to be seen in the Diagnostic buffer, no interrupt OB is called, and no time interrupt is programmed. Question: How can I reduce the amount of CPU usage whitout decreasing the amount of user programm (FB's, FC's DB's etc), and whitout adding a "sleep" time? Technical Info: S7 version 5.4 SP1 WinLC version 4.1 Profibus attached via CP5613 Visualisation via MP 370 touch Has anyone experianced such a problem before? Ore has anayone an idea how solve this problem? Thank in advance. Henk, Brain Center The Netherlands.

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Simple solution - use a PC with faster CPU. Less simple: - check program scan rate and find out if it must be so high, maybe it can be decreased - optimise program execution - normally many parts of a program doesn't have to be executed each scan (like analogue IO access/scaling, calculations involving data shown on HMI)

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thx jacekd. Indeed a faster CPU solves our problem, maybe a dual CPU is even better. And also decreaing the SCAN rate by reducing the ammount of program wil help. But the problem is that I'm talking about an installation with multiple eqaul SoftPLC's (total = 11). So this means a lot of work/costs. I have got some additional info, see my post below. greetings Henk.

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Hello, I have got an update for my problem: ProblemUpdate: Yesterday i have been inspecting the installation(s) and got some new interesting info: There are inexplicable CPU Peak loads Explaination: Due to a yet inexplicable reason there are Peaks loads caused by the the WinLC exacutable. Somehow this exacutable performs a task (maybe in case of an error?) that takes a lot of CPU load. The problem of losing OPC data due to a high CPU load only occurs when there ia a peak CPU load. Has anyone experianced this before, and maybe has a solution? Thanks in advance Henk, Brain center (Philips) The Netherlands.

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You could try upgrading to WinAC RTX 2005. I have a couple of V4.1 running without any problems but I am not doing any OPC.

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Hello all, The problem is (partially) solved, but i can't explain my solution. This is what i have done: setting 1: The setting in situation 1 is 15ms mimimum cycle time and 1 ms sleep time. So the total exucution time is 16ms. (The time needed to proces the program is approx 7ms). These were our default settings. By setting the minimum cycle time we tried to reduce the CPU load and this worked. setting 2: But when i ajusted the settings, sleep time 7ms and minimum cycle time 0ms, i saw a much more tranquil CPU load (see figure below). But i can't explain it. The total exectuin time is now approx 14 ms, and that is even faster!! I'm satisfied with this solution, the loss of OPC date no longer occurs beacause the Peak loads are gone. But i would like to be able to explain my solution, can someone? Thanks Henk. Edited by hanky

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