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Unified panel make logs without input change

Created by: AutoGen_6284270 at: 8/1/2023 1:55 PM (5 Replies)

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8/1/2023 1:55 PM	Rate (0)
AutoGen_6284270 Joined: 10/13/2022 Last visit: 6/27/2024 Posts: 7 Rating: (0)	Hi there. I have unified panel MTP 1200 in my automation station (it is electrical station that consists of network grid, diesel engine and battery). I want to know when my circuit breaker operates when there is a power outage and the diesel engine starts. So I made log lists to know which execute first and in which order. And it is working. But the problem is there are too many logs, I would say false logs that didn't happen for real. I realize it is happening when someone is using a touch panel (I usually use Webclinet and there is no problem). If someone is using the panel it generates these logs as in the picture below. As you can see, the panel generates 5 same signals (logs) at the same time. We were not operating with circuit breaker, it happened spontaneously. Does anyone know how to get rid of these false logs? Thank you Attachment Bez naslova.png (293 Downloads)
	Last edited by: Jen_Moderator at: 08/02/2023 05:53:29 Text formatting optimized
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8/1/2023 6:35 PM	Rate (0)
Stefan Arcularius Platinum Expert Joined: 1/21/2013 Last visit: 1/17/2025 Posts: 3436 Rating: (541)	Hi, When translating your alarm texts, I will assume that the displayed messages are user-created alarms. Without additional information, I will also assume that they are discrete alarms. Am I right? In this case, my first guess is that it's the PLC programming. After all, I have seen similar behavior many times before. So let me explain my observations. For a fair number of PLC programmers, it is common practice to reset the array tag used for discrete alarms before writing the individual alarm bits within the same function or function block. This is fine for the PLC, but not for the HMI. This is because HMI communication is acyclic to the PLC program cycle. So it is possible for the HMI to read the data in the short time between resetting all the alarms and rewriting them. Since this happens only a few times, it appears to the HMI that the alarm has gone away for a short time and then reappeared. See FAQ "Why is data of the HMI system or the web server sometimes overwritten in the S7-1500?" for a further description of this effect. Since using the web client puts a different load on the panel than the HMI GUI, the communication cycle may be slightly different, which could explain your observations. However, I would still expect to see the effect described, but perhaps with a slightly different frequency. Or maybe I am completely wrong and the reason is something else. In that case, please provide more information so that I do not have to make assumptions. Kind regards Stefan

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8/2/2023 5:48 AM	Rate (0)
AutoGen_6284270 Joined: 10/13/2022 Last visit: 6/27/2024 Posts: 7 Rating: (0)	Yes, you are right. I use user-created alarms, discrete alarms. Sorry, I didn't write all the information at the beginning. I also use S7-300 PLC. Based on what you write, I guess there is not much I can do to fix my problem. I tried first without DB and it was happening. Then I tried with DB and it is happening again. Also, as I can see, it is happening only to alarms that are classified as information. Alarm, warnings and notifications are not giving these false alarms.
	Last edited by: Jen_Moderator at: 08/02/2023 05:54:09 Text formatting optimized.
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8/2/2023 6:09 AM	Rate (0)
Stefan Arcularius Platinum Expert Joined: 1/21/2013 Last visit: 1/17/2025 Posts: 3436 Rating: (541)	Hi, Even if you are using a S7-300, you can optimize your program. First you should check if the bits are written more than once per CPU cycle. As I described, first reset and then - if the alarm should be displayed - set to TRUE. If so, try to change the program so that the variables are written only once. To TRUE or FALSE depending on the machine state. Kind regards Stefan

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8/2/2023 6:48 AM	Rate (0)
AutoGen_6284270 Joined: 10/13/2022 Last visit: 6/27/2024 Posts: 7 Rating: (0)	Stefan Arcularius Hi, Even if you are using a S7-300, you can optimize your program. First you should check if the bits are written more than once per CPU cycle. As I described, first reset and then - if the alarm should be displayed - set to TRUE. If so, try to change the program so that the variables are written only once. To TRUE or FALSE depending on the machine state. Kind regards Stefan Thank you for your answer. It may be a bit stupid question. But can you explain me how to check if the bits are written more than once. Where should I look that? I am using Tia Portal 17.

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8/2/2023 9:02 AM	Rate (0)
Stefan Arcularius Platinum Expert Joined: 1/21/2013 Last visit: 1/17/2025 Posts: 3436 Rating: (541)	Hi, The cross reference list helps you to find write accesses to variables. The chapter "Show overlapping accesses in the cross-reference list" in the manual may be helpful. However, depending on the programming, not all accesses may be found. Kind regards Stefan

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