PowerFlex 7 Series Hour Accumulator

I have a customer that has a VFD that stopped unexpectedly and no one can say whether or not the drive faulted. The drive records the fault code and time for the last 8 faults. I don't know when the last fault was recorded, was it Yesterday, last week, or 3 months ago. The time recorded is a free-running hour accumulation.

According to AB tech support, the only way to figure out when the faults happened is to cycle power to the drive. A snapshot of the current hour accumulation will be stored in the "Power Up Marker" parameter. This power cycle is only required if you don't know when the drive was last powered up. If you know the time when the "Power Up Marker" was updated, you can calculate the "real time" of the fault by subtracting the fault time from the power up marker and subtract that from the "real time" at power cycle.

My question to AB tech support was: "If the drive has a free running hour accumulator, how can I access it so I can see the accumulation without doing a power cycle?" Answer: "Can't be done."

Does anyone know of a trick to read the live hour accumulator via HIM, RSNetworx for Devicenet, Drive Executive, Explicit MSG, or whatever?

Yeah, I had to sort this out sitting atop a crane on the shore of the Gulf of Arabia.

Let me see if I can find my notes.

It's in the Diagnostic Objects somewhere.

The reason I didn't pursue it more is that the drive doesn't have a battery-backed clock: the timer only increments while the drive is actually powered up. Since these drives were spending a lot of time powered down (during comissioning) I really had to way of knowing if the drive had faulted or if the power had just been switched off.

I ended up watching the drive for a Fault bit, then timestamping it inside the ControlLogix.

For your purposes, if the drive isn't spending a lot of time powered down, the DPI clock might help.

Edit: I think I used the DPI Time object, as described in the 20-COMM-D user manual appendices. All the project files for my experiment were on a hard drive I had to give back as work product to my former employer, though.

Thanks for your help Ken. You've pointed me in the right direction again. I found the DPI Time Object in the 20-COMM-D manual. I will give it a try when I get a chance.

This customer is supposed to be trending the drive fault bit and fault code now so the next time this drive faults it will be easier to troubleshoot.

For future projects, I think I will be adding time stamp extensions to my motor UDT.