The G540 is not wrong concerning the VFD output. It is just easy to misunderstand what it means.
ANALOG OUTPUT: This is a 0V to +10V opto-isolated analog output intended for use with VFD drives. VFD OUT goes to 0VDC while the G540 is disabled. Connect VFD GND, VFD OUT and VFD +10V to the VFD drive inputs. Make sure the VFD drive positive voltage does not exceed +12VDC. Do not short VFD OUT to any other terminal. Do not reverse polarity to VFD GND and VFD +10V or the G540 may be damaged.
A VFD will generally provide a 10V supply for the purpose a 'remote' control such as the G540 provides. If your not familiar with VFDs though it can be a bit confusing as to what the G540 VFD output does.
After talking with Paul on the phone the other night we discovered a few things.
1) The Mach profile he was using was corrupt. This happens every once in a while and it is hard to diagnose. In this case Mach would not turn output 2, there may have been other issues but this one stuck out. I sent him another copy of the Dyna 2400/G540 profile and output 2 was now working.
2) Output 1 (spindle relay) was showing it was on in Mach 3 but the relay was not physically turning on. This turned out to be a loose connection to the relay coil.
3) There was no output from the VFD output of the G540. This problem is still open, it looks like it might be a wiring error between the spindle controller and the STDR-4C, a friend is going to help him double check the wiring. It could also be in the G540 or wiring between the rear panel of the controller and the G540.
Problems like this can be tough to troubleshoot as there are multiple little things adding up to make for a big confusing mess. The trick is to break the big problem into small bits. For example the first thing we checked was that the Ports&Pins and spindle setting looked right. Then we checked to see of the outputs actually triggered the relays. This is how the problem with the corrupt profile was found. With a fresh new profile the relay on Output 2 worked but Output 1, the spindle relay did not. It showed in Mach as though it was being triggered so this indicated a possible wiring issue.
As someone one told me, the best way to eat an elephant is one bite at a time. The same goes for troubleshooting a complex problem, break it down into bite sized pieces and take care of them one at a time.