Detecting PowerFlex 525 Ethernet Comms Fault

[papacroft]

I'd like to be able to detect if the Ethernet Comms falls over between my PLC Ethernet card and any of the 5 PF525 inverters I have connected to it.

There's some data types - module defined members e.g Faulted, Ready, Active etc. There's one call CommFreqCnt, but not sure what that's for. Any advice much appreciated on a way to detect falling over.

(Background: The Ethernet card is 1756-ENBT/A connected to a managed cisco switch which connects to an unmanaged switch which has the 5 inverters.

Basically after improving robustness, so that I can issue a shutdown of system if I have a comms failure to an inverter...

Thanks in advance.

 

[Ken Roach]

There's a whole reference manual about doing network connection diagnostics in the Logix controller family, but fortunately this is fairly straightforward.

https://literature.rockwellautomation.com/idc/groups/literature/documents/pm/1756-pm015_-en-p.pdf

You will use the Get System Variable (GSV) instruction to read the EntryStatus value of the Module object for each PowerFlex that's in the I/O tree.

The highest 4 bits in the 16-bit INT that you get back from that instruction represents the status of the connection. When the value = 4, then connection is established and running. Any other value, it's broken or un-established, or resetting.

What I do is run the GSV every few hundred milliseconds, putting the Module/EntryStatus value into a tag I name "ThisDrive_EntryStatus_Raw".

Then I divide ThisDrive_EntryStatus_Raw by 4096 to shift the value 12 bits to the right, putting the result in ThisDrive_EntryStatus_Value (a DINT type tag).

Then I just evaluate whether ThisDrive_EntryStatus_Value = 4, and turn on a "Connection_Status" BOOL.

 

[mister x]

Tagged for future use.

 

[papacroft]

Thanks Ken - I'll check this out

 

[bornwild]

Thanks Ken,

Out of curiosity. Why do we need to take the entry status? Is there a difference if we the attribute fault code like attached.

 

[_Dock_]

The fault flag will set high on a 525 when a net loss occurs. That is only IF it had a valid connection first, then lost comms. If the drive never connects after power up then the net fault loss will not be detected.

If the system is small enough I just use a GSV for the IO status instead of looking for status of each drive.

 

[rupej]

The fault flag will set high on a 525 when a net loss occurs. That is only IF it had a valid connection first, then lost comms. If the drive never connects after power up then the net fault loss will not be detected.

Interesting, I never knew that. I guess the fault bit isn't very helpful for comms loss then since you don't know if it's a comms loss or an actual fault, if you get the fault bit at all.

 

[JZerb]

The fault flag will set high on a 525 when a net loss occurs. That is only IF it had a valid connection first, then lost comms. If the drive never connects after power up then the net fault loss will not be detected.

If the system is small enough I just use a GSV for the IO status instead of looking for status of each drive.

I've always used this. Is that the incorrect way of going about it?

https://rockwellautomation.custhelp.com/app/answers/answer_view/a_id/552012