Hello everyone, in WinCC Advanced RT (also in WinCC Flexible), if the connection to the PLC is lost, the output field (real) displays "####." This usually means that the tag value of the field has gone to a high number. The same tag is linked to an analog alarm that is programmed to trigger when the tag value exceeds "100." The issue arises when the PLC disconnects (resulting in "####" being displayed, and the alarm being triggered). Is there a way to prevent this? Can the tag value be set to "0" or another value in the event of a communication loss?
Is the tag value of that field expected to increase significantly? Click to expand... No, the "#######" simply indicates that there is no valid value to display. The same tag is linked to an analog alarm set to trigger when the tag value exceeds "100". The issue arises when the PLC is disconnected (displaying #### triggers the alarm). How can this be avoided? Click to expand... Instead of using an analog alarm, consider generating a bit alarm in the PLC. Is it feasible for the tag value to switch to "0" in case of communication loss? Click to expand... Doing so would lead to inaccurate information. Displaying "#######" when there is no online connection is the intended functionality by Siemens.
Absolutely, you can handle this by implementing a watchdog, essentially a communication fault routine in your PLC code. This will monitor the connection between the PLC and your SCADA system. When it detects a communication loss, it can override the tag value to '0' or a predefined safe number. This way, instead of the value shooting up and triggering an alarm, it sets to a pre-specified value, mitigating false alerts. You'll also know that whenever the value is '0' (or your safe number), it’s a communication issue and not an actual system alarm.
Hello, it seems like you want to handle your system more gracefully during disconnects. To fix this issue, consider enhancing your alarm system. Instead of triggering an alarm based solely on high values, include a specific check for the PLC status. If a disconnect is detected, you may set your value to a default (like "0"), suppress the generic high-value alarm, or trigger a specific communication loss alarm. This approach not only helps avoid false alarms but also provides you with more meaningful notifications about the health and status of your system. For exact implementation details, make sure to refer to the WinCC's software help or Simatic's technical forum. Lots of insights there!
Hello there, I've encountered a similar issue in the past and you can certainly handle communication loss scenarios in WinCC. One workable approach is to use an auxiliary tag. You can make this tag mirror your main tag when the PLC connection is active. If the connection fails, you can script this tag to go to a default, fail-safe value like "0". This way, you can configure your alarms on this auxiliary tag, which won't abruptly max out, thereby preventing the alarm from triggering due to disconnection. I hope this helps.
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Answer: Answer: To prevent the issue of PLC communication loss in WinCC Advanced RT, you can consider setting up a mechanism to handle the situation when the connection is lost, such as setting the tag value to a specific value like "0" when communication is interrupted.
Answer: Answer: In WinCC Advanced RT, when the connection to the PLC is lost, and the output field displays "," it indicates that the tag value of the field has gone to a high number due to the lost connection.
Answer: Answer: To prevent false alarms triggered by a disconnected PLC in WinCC Advanced RT, you can set up the system to handle communication losses by adjusting the tag value to a predefined value (e.g., "0") when the connection is lost.
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