What can cause an Err5 fault on the S-Flex ATV212 drives?

Issue:
What can cause an Err5 fault on the S-Flex ATV212 drives?

Product Line:
Altivar ATV212  S-Flex

Environment:
All with an serial coms setting turned on.

Cause:
Started to get the Err5 fault after setting F829 to Lowworks control

Resolution:
Err5= is a serial communications error.  If you program F829 to be controlled over the network make sure you are sending a signal within the programmed timeout period.
Check timeout setting on F803
Check the remote HMI cable if they used.
Check the F829 settings  try setting F829 back to 1 to see if it will clear the Err5.