etherCAT:disable Distributed Clock kills Digital outputs

[viScience]

I have seen this happen on one of my cRIO's.  I had disabled the distributed clock on the etherCAT chassis and forgot about it until

diagnosing a problem with digital output no longer working in the extended chassis.  After renenabling the distributed clock the digital I/O started working correctly.

Has anyone else seen this problem?  I was under the impression that this distributed clock only proved hard frame sync to the extend chassis and all I/O should work

without it.

[Robbob]

When you disabled the distributed clock, were you using 'unsynchronized' or 'synchronized to EtherCAT frame'?

I'll give this a try when I get in tomorrow and see if I can replicate it.

[Robbob]

Sachsm,

So, after disabling the Distributed Clock, my digital I/O still worked when using the 'unsynchronized' option, both with while loops and timed loops synched to scan engine. When I used 'Synchronize to EtherCAT Frame', my I/O no longer worked.  The only reason to ever disable the distributed clock(also known as free-run mode) would be to use third-party masters that have difficulty with the distributed clock. Is there a reason you were disabling it?

[viScience]

Yes, I was originally trying to diagnose a problem with the Software Sync (1588) beta and was advised to try to disable the distributed clock.

I am finding that the problem on my cRIO's (2 of them had this problem) is now gone and I am not able to replicate.  Somehow the cRIO was put into

a funky state and even in the DSM I was not able to set a Digital Output.  Not sure what caused the problem but thought it would still be good to throw it out there since it was certainly real while it was happening.