[PhoenixMetal]

I am putting together a 3 axis CNC mill system using the KFlop and KStep. There is a VFD which is used to power the spindle.

The VFD has 5VDC and 24VDC auxiliary outputs in addition to its normal VFD motor output. It would be convenient to use this 5VDC supply to power the KFlop and the 24VDC for the limit switch and input circuits. This way, I would not need to install dedicated 5VDC and 24VDC power supplies.

My question is - will this work acceptably, or do you expect excessive noise on the 5V supply from the VFD such that it might cause problems?

[Jade York]

As long as you are not exceeding the current you shouldn't have any issues, it should work fine.

[TomKerekes]

Hi PhoenixMetal,

If the current is sufficient it should work. But are the 5V and 24V GNDs common? If they are common then you will defeat the opto isolation of the KSTEP inputs. That would couple any noise picked up by the limit switch wiring into KFLOP GND that would not be coupled if an isolated 24V supply was used.

HTH
Regards

[PhoenixMetal]

Ah yes - the 5V and 24V grounds are common. I will get a separate dedicated 5VDC power supply to maintain the isolation. Thanks for the input!