PAC8000 SIL2 controller - Memory usage and free memory.

Hello ,

Is there any way to find our the memory usage and free memory in the PAC8000 controller 8851-LC-MT

I tried to locate in the WORKBENCH 8.4 sim 8, but could not find a way to do it?



  • The Controller Statistics feature displays scan time breakdown, system parameters, and event logs. To access the Controller Statistics screen, expand the controller node In the Project Explorer and double-click. The top portion of the Statistics tab shows the breakdown of the controller scan time so that the most time consuming portion of the execution cycle can be determined. Other diagnostic data is also displayed, including the number of controller failovers, refreshes, and warm starts. The bottom portion of the screen shows the controller event log. The event log shows the last 512 events that have occurred in the controller. Such events can be triggered by channel failures, module failures, downloads, etc. For more information regarding Controller Statistics, please refer to the Controller Statistics section in the online Help.

    SafetyNet CPUs have 512kbytes RAM and memory shouldn't be an issue for a safety application. If memory is exhausted, then you can split an application across two or more SafetyNet controllers and use safe peer-to-peer networking or hardwired I/O to exchange signals. However SafetyNet is mature so modernisation to a more recent safety system is suggested.
  • In reply to Steve Ward:

    Thanks, but where specifically can i see the memory consumed and memory free that is available.
    Also the CPU usage which i see is 94% which is kind of misleading. Is there any way the actual loading of CPU can be seen or verified?
  • In reply to Vikram Pungaliya (Prime Controls):

    CPU usage is essentially meaningless as the CPU runs as fast as it can. You can use the Controller Statistics, Statistics tab to see the cycle time in milliseconds which is more meaningful. However in my experience, process safety systems don't need to be fast and you typically have a five second delay before doing anything to avoid spurious shutdowns (ESD) or deluges (F&G). BMS may need to be faster (and BOP faster still but SafetyNet isn't used in BOP). For more information regarding Controller Statistics, please refer to the Controller Statistics section in the online Help.
  • In reply to Steve Ward:

    Agree , however the client insists on seeing the total memory and free memory in the system (which can be easily seen in other make of PLCs). The Controller statistics screen unfortunately does not show this....So any help in that direction where we can see the KBs total available and free KBs available, would help.