Why does my cFP-2120 show CPU usage at 100% in the Real Time System Manager with no VIs loaded?

[RSystems]

Hello - I'm new to cFP and am just setting up a 2120 controller for the first time.  After creating a real-time project based on the tutorial shipped with the real-time module, the System Manager is showing the CPU of the 2120 pegged at 100% with mostly low-priority tasks.  The System Manager shows no VIs currently deployed.  Is there a configuration setting that I'm not aware of, or a way to clear out unnecessary tasks?  Thanks,

Al

[Devin_K]

Hi Al,

The 100% usage is due to the fact that by default the cFP controller continually polls the I/O modules when there is idle time.  Have a look at the following article: Why Does the RT System Manager Have 100% CPU Usage on FieldPoint?

As explained in that article, you can add a pause time to your real-time controller so that it waits between polls, lowering the CPU usage.  You can add this pause time by finding your cFP under Remote Systems in MAX, clicking on the bank (cFP-2120 @0 Bank), and entering a value for Pause (ms) on the Bank Configuration on the right side of the screen.

[RSystems]

Hi Devon,

Thanks for your response - I tried changing the pause time (to 2mS and 10mS) and rebooting the controller, but the CPU usage stays at 100%.  In the Why Does the RT System Manager Have 100% CPU Usage on FieldPoint? article it refers to this as "normal and expected behavior" for cFP.  No problem, I just didn't want to start writing software thinking there was something wring with the hardware.

Thanks,

Al

[Devin_K]

Hi Al,

It is expected that CPU usage will be 100% if you have the default pause time of 0 ms.  However, if you are correctly changing the pause time, you should see this value decrease accordingly.

The important thing to remember is that the configuration settings you use in MAX are not neccessarily the same as the settings in your LabVIEW project.  It is possible that you were correctly changing the pause time in MAX (by following the instructions in my previous post and clicking "Apply"), but when you went to run your program the project settings were being downloaded to your controller, changing the pause time back to 0 ms.

To change the pause time in your LabVIEW project (LabVIEW 8.0 and later), right-click your FieldPoint target and select "Properties".  Go to the "Bank and Network Module" tab, change the pause time, and click "OK".  After this you need to deploy the settings to your target.  Right-click your target in the project and select "Deploy".  You should now be using the proper pause time that you set.

If this still doesn't work for you, please let us know and I will try to determine what is causing this behavior.