Update controls on Hendricks 2008 CNC

[cncsnw]

You need to be clear on the difference between Centroid PLC outputs that go to VFD inputs; and VFD outputs that go to Centroid inputs.

H11 on the Oak board is for Centroid PLC outputs. Those are all relays, each with their own common terminal. They are used for things like "Run Forward", "Run Reverse", and "Reset". As you can see in your VFD diagram above, it expects you to close its "SC" terminal to "S1", "S2", "S4" etc. when you want something to happen. Your external 24VDC supply is absolutely not part of that picture. You are taking a connection from the VFD; routing through your PLC relays and maybe your E-stop contactor; and feeding it back to the VFD.

When you asked about "30V" and "48V", I assumed you were asking about the VFD outputs (multifunction relay and photocouplers), since those are the devices that mentioned such voltages. The VFD outputs are used to send information to Centroid PLC inputs, e.g. on header H14 of the Oak board. In a typical installation, you connect +24VDC from your external supply to the PLC input bank commons on Oak/H14; you connect 0VDC from your external supply to the "MC" and possibly "PC" terminals on the VFD; and you connect MB, and possibly P1 and/or P2, to input points. For the usual fault signaling, VFB/MB would wire to Oak/INP10. If you want the PLC to be able to tell when the VFD is actually running vs. stopped, you could also wire from VFD/P1 to Oak/INP12.

[DAYTRIP]

Thank you cncsnw. So on the S terminals you are creating or breaking continuity of the circuit ? Where as the others you need power to achieve the output? I had one circuits class 32 years ago getting my aerospace engineering degree so I tend to get wrapped around the axial and confusing things. I really appreciate your help. Jim

[cncsnw]

In both cases, the device that wants to receive information (the input) supplies an elevated-voltage input terminal and a return terminal, and watches to see whether or not current flows out the elevated-voltage input terminal. The device that wants to send information (the output) selectively closes the circuit between the two terminals, allowing current to flow.

This is what is usually called a "current-sourcing input". Current (at least, conventional plus-toward-minus current) flows out, but information flows in.

If that is hard to get your head around, picture this:
You sit on the roof the a building with a large barrel of water.
A hose leads out of the bottom of the barrel and disappears down into the building.
There is a turbine fitted in the hose that makes a flag wave, or bells ring, or whatever, so you can tell when water is flowing.
I sit in the basement with a valve fitted to the other end of the hose.
I can send messages to you (maybe via Morse code?) by opening and closing the valve.
Water flows down, but information flows up.

That is how a current-sourcing input (the barrel and turbine) and a current-sinking output (the valve in the basement) work.

[DAYTRIP]

So what happens to all the water?….

Just kidding! Both explanations make sense. Doesn’t mean I won’t screw it up but I understand and appreciate your help. The only reason I felt comfortable doing this was because of this forum and Marty’s YouTube.

Got the controls to the drive wired. Close to continuing the start up process.

[cncsnw]

So what happens to all the water?….

A valid question. One party or the other is responsible for supplying a pump, to return the water from the sump in the basement back to the barrel on the roof.

In your installation, the "pump" (24VDC supply) for the signals from the PLC outputs to the VFD is built into the VFD; and the "pump" (again a 24VDC supply) for the signals from the VFD to PLC inputs is your external switching supply (probably PS1, the RQ-65D that came with the Allin1DC).

[DAYTRIP]

Makes sense. The fact that both communicate adds a twist for me.

[DAYTRIP]

Is there any issue pulling 120v power from one leg of the 3 phase vs using the T1 transformer on the centroid schematic? I have a second power supply to create 24 Vdc for the estop loop. My power is coming thru a transformer which converts the delta to wye and reduces noise. It proves a neutral connection so I would bring that back to give me the 120v..

Thanks for the thoughts. Jim

[cncsnw]

As long as you bring in a dedicated neutral wire (separate from ground) I think that is legitimate.

The neutral should be grounded at its source (in this case, the wye point of the transformer). See "separately derived system".

[DAYTRIP]

Ok, I watched about 10 videos and read about the same post. Looks like I tap the x0 (neutral) and I also bond that to the ground that runs back to my panel? I was contemplating running neutral back to panel but that doesn’t appear to be desirable or required?

Thanks as always!

[cncsnw]

Since your transformer secondary windings are isolated from the primary windings (it is not an autotransformer), the secondary voltages will "float" with respect to ground, until you firmly ground them at some point. That point should be X0, the wye center.

Since the transformer is now the voltage source for the new system, it is to the transformer that neutral currents need to return. If you were to wire the neutrals to the service panel neutral, then the return currents would have to flow through the X0 bonding (grounding) conductor to get back to the transformer.

To avoid that, the neutrals should come from the X0 tap of the transformer.