At our plant we have control logix with devicenet and flex i/o. 3 of the cards lost power (still don't know why) all of the Solas have come back on and are putting out 24VDC, but there is still a card that says there is no network power. I have already tried cycling all devicenet power and even the proccesor, but nothing has worked. Wondering if anyone has an idea about what to try next or what may have caused this to happen (it has happened befor but came back on when i cycled power). Thanks for any feedback.

Do you have power between pin 1 and 5 at the device that says it doesn't have power?

If the 1756-DNB is reporting "No Network Power", it's not kidding; it really does not detect 24VDC between pin 1 and pin 5. It could be as close as the connector on the module, or somewhere else in the cable system.

If you genuinely have 24 VDC on the connector of the 1756DNB and it still reports no network power, then the DeviceNet transciever is blown up and the card needs to be replaced. If that's the case, get ready to find some sort of wiring fault in your system that introduced a high voltage at some time.

Just yank the card out of the rack and stick it back in again.

See if that clears it.

There was 24VDC between pins 1 and 5 @ the cable end. I pulled the card out, put it back in, and it started working again. I still don't know why 3 of the 5 Solas in the plant all shut down @ the same time though? Also, what made them come back on, I cycled power, but that didn't seem to help; they just came back on on they're own and all but 1 card started working again. The 3 Solas are also on different circuits so I don't believe that there was a short some where.

When you say the 3 solas, are they powering different parts of the devicenet? If they are, make sure all of the commons are tied together. Also were the devices that went offline all powered off of the same sola?

There are 5 cards, 5 solas, 5 devicenet circuits, and 1 Sola powers 1 circuit with 1 circuit per card. All the commons in a circuit are tied together. All the devices that were on the 3 circuits that lost power did go off-line. When this happened there was still 120VAC apllied to the card, but there wasn't 24VDC out.

It must be those "Homotrons"....You know, those "Queer" electrons....

when your sola dc power supply shut off and you have 120vac applied to it that means you have a short some were.