That's a little open-ended.  What size (power) VFD?  Define GUI... an LCD touchscreen or several knobs.  What is the intended purpose?

Several of Hitachi's VFDs are controllable through a removable front panel using RS-485.

Dan - Owner
http://www.Hi-TecDesigns.com

Red Lion's HMI line, G3, has extensive Modbus master capability.

In fact, Red Lion takes the display off the HMI line, and packages the communications in a DIN rail mount box called the Data Station which is great for blind Modbus'ing.

Give Red Lion a call and they'll tell you what you need.

http://www.redlion.net/g3features/

I just got an email that looks like Unitronics might do that, too, but their web site 404's.   

www.unitronics.com/

Thanks guys; I'll give those a look.

~Mark

You can find plenty of them that have RS-485 ports but the trouble comes in with the software to implement the control commands for the drives.

There may be standards but each manufacturer seems to wanna go for the whole pie and come up with their own protocol.

If it's speed control only the good ole 4-20 ma is present on most drives.

I once though of using the Rabbit BL1810 for drive control but i would have had to write my own C code for the protocol.

 

I would expect some of the Automation Direct HMI's would do Modbus master over RS485. If not, there are other HMI products avaialable.