4/30/2018 5:59 AM | |
Posts: 59 Rating: (0) |
Timers are sometime not working at S7-1611-1PN; CPU cycle time is set to 10 ms ; there are networked two CPU 1511-1PN , One Simatic HMI TP15 Comfort and Two LOgo 8 PLC and my user application program is also of medium size. Please advise whether I will increase CPU Cycle Time and IO exchange time to solve the problem. Thanks ------------------------------------------------------------------------------------------ |
Last edited by: Jen_Moderator at: 4/30/2018 10:36:51 AMNew subject after splitting |
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4/30/2018 8:16 PM | |
Joined: 7/7/2010 Last visit: 10/11/2024 Posts: 15292 Rating: (2427)
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Screenshot(s) would be very helpful. Are you saying you changed the fixed cycle time of 10 to 150 ms rather than the watchdog time-out of 10ms to 150ms? The default is 150ms is why I ask. How much communications load % are you allowing in your PLC hardware configuration for the 2 1511's? The default is 30%. Perhaps bump it to 50% just to be safe you are not starving your HMI or other PN devices. As for timers, IEC_TIMERS (like TON/TOFF) require the timer.Q output to be "looked" at somewhere in the program logic. The output of the TON at the Q output is useless, well, unless you stick a NO timer_DB.Q right there at the TON's Q output. If you do that, things might work better. What I do is, at least in ladder, run a parallel connection around the timer block with the timer_db.Q NO the first thing in that parallel connection, then complete whatever relies on the timer's Q output. Doing this in that exact place has resulted in predictable timer performance. There are many forum topics related to s7-1200/1500 timer Q outputs not behaving as expected. The above approach makes them behave.
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science guy |
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5/1/2018 6:06 AM | |
Posts: 59 Rating: (0) |
Dear Sir, I am busy with the commissioning activities at site; I will provide the screen-shots and other relevant information shortly. Thanks for your support.. |
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