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      System Watchdog
      • 19 Sep 2024
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      System Watchdog

      • Updated on 19 Sep 2024
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      Article summary

      Verifying communication with Koios

      System Watchdog

      The primary method for verifying that Koios is online and communicating with your control system is by using the System Watchdog. The System Watchdog is an integer value that increments from 0-999 once a second. This value can be mapped to the control system using parameter mapping. To do this, go to System > Local Values > System Watchdog and click on the mapping tab. From here you can follow the parameter mapping guide to write the int_value parameter to an output tag. If the System Watchdog value stops incrementing in the control system, it could be related to any of the following issues:

      Issue

      Resolution

      The machine that Koios is running on is shutdown or no longer on the network.

      Ensure that the machine is running and that it still has access to the network.

      A critical system service has shutdown.

      Ensure that the Predict Engine and Data Collector services are running. Go to System > Services.

      The tag or device responsible for writing the watchdog value to the control system is inactive or failed.

      Check the device and tag’s status Koios.

      Using this in logic

      Any time a prediction is used in the control system, you should also take into account that the watchdog is in an OK state. This is commonly done by storing off the previous scan value of the watchdog and comparing it to the current value on the next scan. If the values are not equal, this means that the watchdog value is being incremented and there is good communication between Koios and the control system. A basic implementation of this could looks like this, where the following function blocks serve these purposes:

      • Not Equal: Ensures that the current and previous value are different.

      • Off Delay: Allows some wiggle room on a missed scan.

      • Move: Saves the current value as the previous.

        • Be certain that the move operation occurs after the not equal comparison!

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