VFD HY only rotates at 12000rpm

[Doddy]

SaporeCNC,

Sorry, I shouldn't presume any experience:

You're discussing a system where the Spindle is being controlled by an analogue voltage, between 0-10V, provided via Mach3 through the CSMIO. To understand if your problem is with the Mach3 set-up, or the CSMIO, or the VFD, the easiest indicator is the analogue output from the CSMIO to the VFD.

I've read into your description that the FOW control works (so issuing an M3 command starts the spindle, at 12000RPM), but any speed command fails to change the RPM. So, if you issued "M3 S8000" in the MDI, that the spindle will operate, and the VFD will display 12000 RPM. Please correct me if I've misunderstood.

From here it is logical to measure the analogue voltage output from the CSMIO, by connecting a DC volt meter (or a DMM on a DC voltage range) across the ACM terminal on the VFD (black/negative) and the VI terminal (red/positive).

A properly configured Mach3/CSMIO would output around 10V with the "S24000" setting. It should output around 5V with the "S12000" setting, and around 2.5V with the "S6000" setting. If it does, then the problem likely lies with the VFD, and it's settings.

The reason I asked for three settings is to verify that the CSMIO/Mach3 is not saturating the output from the CSMIO (e.g. if the S24000 and S12000 both output 5V, but S6000 does give 2.5V, then it would look as though the CSMIO analogue output is limited to 5V (for whatever reason - and I don't know the CSMIO and would advise no further). Also, if the S6000 also output 5V then I would seriously look at the Mach3 / CSMIO configuration, as I would expect that the DAC on the CSMIO wasn't being driven by Mach3.

If, however, the CSMIO does output the 10V/5V/2.5V expected for S24000/S12000/S6000 then you can be reasonably sure that the CSMIO/Mach3 are correctly configured, and we can concentrate on the VFD settings.

I have briefly looked at the register settings for the VFD, that you provided, and they look at first glance to be correct. But, if the voltages out of the CSMIO into the VFD are broadly as expected at different speeds then we can spend more time looking at the VFD set-up.

One other question: You say the speed is 12000RPM. Is this a fixed, exact 120000, as indicated on the VFD? (my reason: it's unlikely that you'd get a precise analogue output of exactly 5V from the CSMIO to give the exact 12000 RPM... it might indicate that the VFD is not sourcing it's speed control from the external VI input).