High CPU usage on 1756-ENBT

Meh. I don’t trust that 100% stat in the ENBT. Flaky junk. I have to admit that I jerk them out at first opportunity. The EN2T is much better.

Things to try in the meantime:

  • Run your concurrency up on your drivers. You have ~128 CIP connections to work with. Consider 12-ish for each of the seven CPUs.

  • Split UDTs out of your AOIs as described in the linked topic, if practical.

  • Anything else in the AOIs that is display-only or configuration or tuning, move to a leased group or scan class.

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And I would be remiss if I failed to mention the option to use class one connections–I/O or producer/consumer–via my module:


Class one CIP connections seem to be a much lighter load on the PLC and comm cards even with blistering RPI settings.

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Only reason I went looking into this is because the citect driver that was also looking at the same PLC kept crashing. AFAIK this hasn’t occurred on the live system, but I am cautious of it. Thanks for your suggestions on how to improve things. Modifying the polling to be a bit smarter is probably the most practical option moving forward.