Centroid Community CNC Support Forum

I'm new to this form and I have some questions about the schematics for the Clear Path motors. I have downloaded two schematic the first one is for wiring up one clear path motor S14971.DWG. The other schematic Drawing is for wiring up three clear Path motors S14972.DWG. The First drawing S14971.DWG does not show any relays being hock ups on this drawing at all. The next drawing S14972 is for wiring up three motors this drawing shows relays being hocked up. I'll call the first relay the Back and the second relay Front. I know the back relay is the one that is hooked up with the Acorn CNC board and it is not showing any wiring hock ups. But the front relay board shows this relay being hocked up instead of the back relay. do I add another relay board or is this drawing screwed up

drawing is correct.

So your saying I have to have two relays boards. And which one is correct?

The two schematics show 2 different suggested ways of connecting your system. The 2nd relay board shown on S14972 connected to H10 is optional for outputs to your peripherals (Vac, Coolant, hydraulics etc) if needed.

The choice is entirely yours

Look carefully at how the three ClearPath servos are wired to the 1st relay board. Their HLFB (fault) signals drive the INPUTS on that relay board. +5VDC is fed to the VCC relay board's power input. 0VDC (GND) is fed to the relay board's GND power input. The ClearPaths' HLFB- signals (Red Wire) are also connected to power supply GND. The ClearPaths' HLFB+ signals (Green Wire) are connected to the relay board's inputs (Servo 1 to IN1, Servo 2 to IN2, Servo 3 to IN3). When a ClearPath servo is NOT in a fault condition, it SINKS current through its HLFB signals. Sinking current means that relays 1, 2, and 3 are normally ON on the relay board. The COMMON input for relay #1's output on the relay board is connected to the Acorn's DriveOK input signal. The N/O signal on relay #1 is connected to relay #2's COMMON input. Relay #2's N/O output is connect to relay #3's COMMON input. Relay #3's N/O output is connected to power supply GND. If ANY of the servo motors faults, its associated relay on the relay board opens and the Acorn's input floats HIGH, indicating that a fault occurred.

If it's easier for you to use screw terminals on both sides of the relay, you can buy relay boards from vendors like Mdflyelectronics on EBay that have screw terminals on both sides of each relay. Just do a search for 4-channel 24VDC relay boards (or 6-channel or 8-channel). The 24VDC model lets you use your 24vdc power supply without needing to use the 5vdc connection. Before Centroid released the relay board for the Model 3 Acorn some users added a six-port NPN bank of relays to their Model 3 boards. Gary Campbell and Marty both released videos on how to use relay boards with the earlier model Acorn.

Ok next question how do you hook up a home all/limit switches. And could you give me an example.

The HomeAll and LimitALL inputs combine all axes into one input, i.e., mechanical N/C homing switches are connected in series such that if any switch opens, an axis home position is indicated, and mechanical N/O homing switches are connected in parallel such that if any switch closes, an axis home position is indicated. Proximity sensors require additional inputs or additional logic to work properly.

There are 8 inputs on a standard Acorn. I use five of them on my Taig mill. One input is used for the EStop. One input is used for DriveOK. Three inputs are used for Homing Proximity Sensors. I use software limits. I also have the 16x16 I/O board that could be used if I needed to sense limits.As a third option, I often use PLCs like the AutomationDirect CLICK series or the AutomationDirect Productivity 1000 series when I need to combine several signals into one signal.

I'm attaching some simple schematics that show some methods that I have used to connect switches and sensors to my Acorn test bench.

IMPORTANT: The Acorn expects devices attached to its inputs to SINK current. That means that if you use proximity sensors, you need to use NPN sensors. NPN sensors SINK current. PNP sensors SOURCE current. The Acorn sources current, so PNP sensors will not work unless you add a lot of additional logic (like a PLC that expects a sourcing input signal). Also, if possible, use NPN N/C sensors. That type of sensor is always ON unless it detects its target, then it turns OFF. That's the same principle used for most EStop switches. If possible, you want sensors to show a fault if a wire breaks or if something comes loose.

Normally Closed mechanical switches can be connected in series. Normally Open mechanical switches can be connected in parallel to a single input if only one axis is moved at a time. Normally Open mechanical switches can be connected in parallel to separate inputs if more than one axis is moved at a time. Most proximity sensors cannot be daisy chained without compromising the signal strength. I connect each sensor to its own input.

Thank you I have a lot of wiring to do thanks for the information I hope some day I might put a pitcher of my machine on this form thanks. I tried the proximity switches ones Before and I don't trust them.

I have another question, I've have a second relay board and I'm thinking about cutting the ribbon to use on the schematics drawing S14972 if I mess this up can I order another wiring harness for my relay board?

Well I guess you can't ask to many questions in one post. I'm new to posting on this form and have a lot of questions. all I no if you have a question then you ask the question in your post. Then you hope some body smarter than you can answer that question. Just like asking siri on your I-phone a question. and yes I didn't listen to my English teacher in school.