Yes. You can program it to use an analog value.
Yes. You are on the right track.
(Thanks for the link to the Danfoss VFD).
Looking at the doc, there are two types of supported analog inputs. NOTE. You should only use one type or the other, NOT both at once!
You can use one of our SNAP-AOA modules connected to pin 60 and 55. They supply 4-20 ma (or 0 to 20 in some cases).
If you have only the one drive, you could just go with the SNAP-AOA-3. It is a single channel module.
Since 4-20ma wiring is a little less susceptible to noise, and you are wiring to a VFD, one of the most electrical noisy devices around.... This is the input type I would be going with.
(That said, you will need a full tech manual for the drive and check if you need a sinking module or not, if not, you will need an external 24v supply to run through our module, so this could add a little to control system wiring).
The other input is terminals 53 and 55. This is a 0 to 10v analog input.
Here, you could go with our SNAP-AOV-5 module. It is a single channel 0 to 10v DC output module.
If you are confident that your electrician is up to the job of wiring things with good grounding etc, then you could use this module if you have some other control signals close by.
The SNAP-AOV-25 is the same, but dual channel. It would in effect simply just replace the pot you are currently using. And you would have one spare channel for even more control.... mahahahahahah (that's my evil control-the-world laugh).
Note you can hook a SNAP-AIMA module to terminals 42 and 55 to monitor what the drive is actually running at.
Depending on how you program the drive, you might not always get it running at what you send it (for example, if it uses an internal PID, your control signal is just a request, not a command).
Either of our SNAP-PAC R1/2 controllers will use those modules.