Help on selecting local/remote control for Danfoss VLT

Hello all.

A client will be using a Danfoss FC302 VLT. It is to be normally controlled over Ethernet/IP. However, in case communications or the PLC go down, he wants to use a digital input to switch it over to be controlled manually via the local interface.

Is this possible? The programming and user manuals aren't very clear on this, and the Danfoss site is no help at all.

If it can be done, which parameters do I change?

TIA.

Hi,

Yes this is possible.

Easiest way to do this is get the MCT10 tool.

Just to get it straight. You want to use a digital input to force the drive into local operation? The button on the drive itself is not sufficient?

Thinking a little bit about this here.

Scenario 1: Your comms drop. PLC still running.
Scenario 2: PLC dies, every things stops.

For scenario 1, you could use the settings as shown in the picture. Force the drive to an alternate setup, and control start/stop and reference with digital/analog signals from the PLC.


For scenario 2, there is nothing you can do. If the PLC is down, you will not have a digital signal available. So you will have to make a decision.
Keep the drive in the current state.
Start or stop the drive.
If the drive is in operation, keep running but go to preset speed.
Etc.

Again, the mct 10 software will make things much easier.

Thanks for that. In the drawing terminal 27 is connected to a local/remote switch. I wasn't aware it can be done on the interface. I'll ask them, the drawing seems to be preliminary.

Yes, that works pretty good.

Alternatively you can install a local switches for local control. Attached diagram how we did it.