325 Limit Error? <resolved>

[ShawnM]

To really simplify this situation I would recommend you wire the rev 3 Acorn and your Leadshine clone drive exactly like this wiring diagram.

https://www.centroidcnc.com/dealersuppo ... 901.r3.pdf

If you want a "really solid system" I'd suggest you remove all that other stuff in the system as it overcomplicates everything and introduces many unknowns and failure points. Not to mention noise and circuits prone to interference. You only need ONE of the breakout boards mentioned by Marty. It plugs into the Acorn and allows you to terminate your step and direction wires from the drives to the Acorn. You could have cut one end off your existing DB25 cable but I'll save that option for another day.

I'd also recommend rewiring the power to your drives, the way they are daisy chained is not correct. Does it work? Sort of. Is it best practice? No.

Consider shielded wire for step and direction signals as well as your limit switches.

Study the diagram above and wire your drive exactly as shown. Do not wire up the enable or alarm outputs. Wire one drive at a time and get it working then add the second and then the third. Then add in the enable signal if it's even needed and then the alarm output to the Acorn.

I'm not sure why you don't have the Acorn control the VFD, it's designed to do this for you. It'll make you life easier.

Just my 2¢.....

[RGSparber]

Shawn,

I do plan to completely start over on my system and exactly follow the docs plus the suggestions made in this thread.

I had a bad experience with Mach3 which was controlling my VFD. While changing a cutter, the spindle began to turn. I was able to get clear so was not hurt. Thus ended my trust in any computer directly controlling the spindle. I'm perfectly happy to manually turn the spindle motor on and off plus manually adjust the RPM.

Thanks,
Rick

[ShawnM]

That’s great Rick, you’ll really simplify and clean up the wiring and with far fewer mix-matched components in the mix will make it a more robust system. Please don’t go cheap on the wire, get good, shielded wire where needed since we already know you have a noise issue somewhere. It’s really not that much more expensive if you shop around.

As for the VFD coming on by itself, it would be impossible with Acorn given the relays and circuits that need to be active in order for it to signal the VFD to spin. Unless the VFD simply melts down on its own. Besides there are too many safeguards in place so this doesn’t happen. It sounds as if it wasn’t wired properly before anyway and you cannot compare Mach 3 and crappy BOB’s and homemade hardware to anything Centroid offers. But I hear your concerns.

Good luck on the rebuild.

[RGSparber]

What shielded cable do people recommend? My home sensors use +24V and COM and are open collector. I assume that my EStop and limit switches don't need to be in coax.

Thanks,

Rick

[martyscncgarage]

What shielded cable do people recommend? My home sensors use +24V and COM and are open collector. I assume that my EStop and limit switches don't need to be in coax.

Thanks,

Rick

Provide the specs on your home sensors Rick. They must be NPN. To activate an Acorn input, they must be pulled to ground.
3 conductor shielded cable is fine.

Marty

[RGSparber]

Marty,

I'm using Inductive Proximity Sensor Detection Switch NPN DC6-36V LJ12A3-4-Z/BX which are open collector NPN. I'm interested in learning a source for the cable you find works best. I see plenty of cable with 2 conductors plus shield that should work but doubt they would be flexible enough to not break over time.

Are you suggesting I use 3 conductors plus shield? I would want the return current to flow in the shield so what would be done with that 3rd conductor?

Rick

[martyscncgarage]

Marty,

I'm using Inductive Proximity Sensor Detection Switch NPN DC6-36V LJ12A3-4-Z/BX which are open collector NPN. I'm interested in learning a source for the cable you find works best. I see plenty of cable with 2 conductors plus shield that should work but doubt they would be flexible enough to not break over time.

Are you suggesting I use 3 conductors plus shield? I would want the return current to flow in the shield so what would be done with that 3rd conductor?

Rick

NO. You need 3 insulated conductors you do NOT use the shield or drain wire for anything other than connecting it to a single ground point in your cabinet. You have 3 wires on the prox sensor you need 3 insulated wires to connect it.

I sent you an email.....

Marty

[ShawnM]

Exactly as Marty stated, you need 3 conductor shielded wire for your NPN switches. You'll need some 22/4 shielded cable for the drive signals. Typically 18/4 is good enough for stepper motor power and you can use 22/3 for the limit switches. If you decide to let Acorn drive your VFD you'll need some 22/2 for that signal. You could use the 22/3 from your limit switches (not use one wire) if you don't want to buy just a short run of 22/2. I also use shielded wire on the main power for the system, power to my motors and the power coming into the drives but that may be overkill for some. Be sure and get some shielded cable for the VFD as well. They make specific cable just for VFD and you can simply search "vfd cable" and find what you need. I don't know the power rating on your spindle but either 16/4 or 14/4 will be plenty. Wire all the shields inside the cabinet to a single ground point in your cabinet. Do not ground the other end of the shield.

Using the shield as a conductor like you mentioned nullifies the point of having shielded wire. The shield has one purpose only, to keep unwanted noise out.

For your system I'd removes EVERY wire I see in your pics and toss it in the trash and start with all new shielded wire routed properly inside the cabinet. You'll be glad you did.

[RGSparber]

This does make a lot of sense.

I believe that the general strategy here is to use the paired wires inside the shielded cable to provide magnetic isolation while the shield tied at one end to the case ground is giving us electrostatic protection. Noise capacitively coupled to one of these cables causes a noise current to flow into case ground rather than onto the Acorn board's COM.

My drive inputs will be a few inches from the DB-25 connector inside a metal box. Why shield that?

I own a RF-30 Mill/Drill that I converted to CNC. The axis drive motors can draw up to 1.42 amps. Am I correct in assuming you are running much larger motors with potentially much larger noise spikes?


Thanks Shawn.

[martyscncgarage]

This does make a lot of sense.

I believe that the general strategy here is to use the paired wires inside the shielded cable to provide magnetic isolation while the shield tied at one end to the case ground is giving us electrostatic protection. Noise capacitively coupled to one of these cables causes a noise current to flow into case ground rather than onto the Acorn board's COM.

My drive inputs will be a few inches from the DB-25 connector inside a metal box. Why shield that?

I own a RF-30 Mill/Drill that I converted to CNC. The axis drive motors can draw up to 1.42 amps. Am I correct in assuming you are running much larger motors with potentially much larger noise spikes?


Thanks Shawn.

It is beneficial to try and shield at least the step/dir signals from the DB25. At least twist the wires. Make sure your step rate in the advanced tab is set to 100,000, Many have used individual wires and had reasonable success. Just use good wiring practice and you should be fine Rick.

Marty