PLC control of VFD

How can I connect an output from a SLC 500 to a variable frequency drive to start and stop the drive without hardwiring the start and stop ?

DH 485, remote i/o, devicenet, controlnet, profibus etc...
It depends on the drive and the processor. Check your drive manual for interface options.
NOTELEASE HARDWIRE THE E-STOP/DISABLE CIRCUIT TO THE DRIVE. Only use the plc to monitor the e-stop circuit.

I'm reaching a little here on the meaning of your question but I think the answer you are looking for is that you would replace the start and stop pushbuttons you see on the recommended schematic with interfacing relays which are controlled by PLC outputs.

The make and model of your VFD might be helpful here as I'm sure someone on this board has come across it before.

As Mike Williams points out, you must consider safety in the design of your system. You have not given enough information to even suggest the proper e-stop response for your vfd. I have found that due to liability, very few people will give you any application specific safety information especially the manufacturers of specialized safety equipment such as light curtains, safety swtiches and monitoring relays. They point you to standardized risk assesment tools and absolve themselves of responsibility (I can't say I blame them in our sue-happy society).

That reminds me of a story from my previous position. I worked for a company that made mass transit door systems and a large part of our systems involved safety door edges. These sense a person obstructing the door during closing and reverse the operator to open the door. We were doing some work with a company in Europe and when we asked them what method they used for safety door edges they got a puzzled look on their faces. When we explained what they were they said, "why would anyone stand in the doorway when the doors were closing?"

Gary, I'd be happy to help you on this but you might want to explain a bit further just what you want to do.

I'm not clear on a couple of things: First, for the PLC to control the VFD you have to wire SOMETHING! Either you wire discreet PLC outputs directly to the VFD inputs to control things like START/STOP, FORWARD/REVERSE, etc. or, second, you wire a fieldbus cable (usually RS-485) and do all your control over the fieldbus.

You may also want to take some drive outputs back to your PLC inputs. DRIVE FAULTED, RUN VERIFICATION, ANALOG SPEED OR TORQUE signals, etc. Again, these can be done with discreet wiring or thru the fieldbus.

Fill us in a little more completely and we'll try to help you.