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Hello,
Just wondering if you got your AB drives to work.
I am going to attempt the exact setup soon.
Thanks
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Folks,
I have three brand-new Allen-Bradley servo drives and a Bob Campbell Breakout board. My plan is to configure the system and operate it with MACH3. My question is about interface the step and direction outputs from the breakout board to the servo drives. All the AB ultra drives can accept step and direction input, but each has two inputs (Step + and Step-) and (Dir+ and Dir-). I can't figure out how to connect this to the breakout board, and I am really afraid of burning up either the controller or the servo drives.
Can anyone help?
Thanks for any advice,
Paul Vogt,
Charlotte, NC
Two of the drives are Ultra 100 and one is an Ultra 3000
Hello,
Just wondering if you got your AB drives to work.
I am going to attempt the exact setup soon.
Thanks
WYOBMF,
Yes! In fact this works very well. There is a secret, and I will have to look through my notes in order to find out what it was. It was a particular jumper setting I think. Anyway it works very well, and no additional hardware was required. Send me an email if you like and I'll dig up more info.
I have bought two of the breakout boards, built two operational CNCs, and have had great fun, made money, and had zero problems.
Best Regards
Paul Vogt
Charlotte NC
pvogt@noltecse.com
Paul,Originally Posted by pvogtcharlotte
I have Allen-Bradley servo drives and a Bob Campbell Breakout board. You mention on the cnczone about some clewer way to get differential step direction on the Ultra3000 to work from open collector output of the breakout board. Could you please share this invaluble infor to the forum members as there may be some doesn wonder arownd of the same dilemma.
Kind regards
If I remember right the Chambel board has active low outputs setup for Gekos and the ultra 3000 uses active high. I think you need an opto-issolator with the Chambel board, I used a PDMX that can be active low or high.
There is no "Secret" Just wire the Common, to the common on your BOB and then Just wire the step and direction single ended.
You can acomplish step and direction control with three wires.
Folks,
I worked this out some time ago with Bob Cambell's help. Here are some notes:
Dear Robert,
I found that once I moved the jumper from M1 to N1, my problem went
away. Also, the step and direction LEDs no longer turn on all at once when the reset button in Mach3 is pressed. Also, the random occurances of the
same fault have stopped.
I'm not an EE so I don't understand what is going on, but it is working
now.
Any final thoughts on the subject?
Thanks for your time,
Paul Vogt,
Charlotte, NC
Then this:
Paul,
What you have done is to turn off the charge pump safety signal.
I will have Jim Cullins the designer of the board to look at it.
Robert Colin Campbell
Bob Campbell Designs
Then this....
Paul,
The charge pump signal is being sent out from Mach. It is a continuous
10 or 12 KHZ signal that is detected on the breakout board. Once the
signal is detected it turns on out-4. You should see the led come on when you press the reset button. The charge pump signal is basically a safety device. If the connection to Mach is broken or the EPO switch is pushed, then the charge pump signalwill stop.
The charge pump signal then enable all outputs and enables the step and
direction signals to go to the drivers.
Robert Colin Campbell
Then this summary:
Robert,
Thanks for the information. Here are some details that someone might
find useful.
1) My application has two Alen-Bradley Ultra100 servo drives (Y & Z) and
one Allen-Bradley Ultra3000 Servo drive for the X axis.
2) The Allen-Bradley Ultra 3000 drive seemed to be immune to the
problem.
3) Both of the Allen-Bradley Ultra 100 drives (100 is an older model)
would quickly fault when the reset was pressed in Mach3
It may take 5-6 presses to trigger the fault, but it would always
happen. The fault also happened sporadicly, for no known
reason in the middle of running a part file.
4) The fault reported by the drives is "Master Encoder Illegal State
Fault"
5) Allen Bradley tech support was only able to tell me "use shielded
cable, it's a noise problem" (gosh, thanks!) (all my
cables are properly shielded)
6) My impression is that moving the jumper to N1 position immediately
solved the problem.
7) The (J24)jumper for the step/direction output is set for GND. This
was necessary to interface to the AB drives.
I may have to double check this, but I'm thinking that the jumper
sets the reference to 0V, meaning the steps are
+5 volt steps, referenced to common, which is at ground. This detail
is from memory, and I will confirm tomorrow.
I hope this is useful to someone,
Robert, I love your product, Thanks for making it.
Best Regards,
Paul
And this suggestion, which I have not done:
Paul,
When the jumper is in M1 and a reset is given the output buffers go into high impedance mode and are floating. With a opto coupled motor drive this is no problem how ever as with you drive having the inputs float makes it very sensitive to noise. In the N1 mode the outputs are always driven so you have no problems. I would try to put a 1k resistor from the step out terminal to the com on the screw terminal on the breakout board.
Sorry for your problem but I am glad you explained it well as I have not had that problem mentioned before.
Thanks
Jim Cullins
Sound Logic
To anybody still following this thread:
I'm trying the same thing, using an ultra 3000 with mach 3 to run my spindle. I've successfully wired it up and mach 3 can turn the spindle at the appropriate RPM, but I'm having a different problem.
It appears that my step increments on my servo are too high, causing very bad vibrations. Has anyone changed any setting in the ultra to make the step increments lesser or greater?
thanks,
Greg
Glenter,
I had to set the scaling in the 3000 to get the proper motion out of the drive. This was easy to do using the AB software. I can help if you're struggling. On my system, the 3000 drives the X axis, and is not nearly as fast as your spindle. I don't know what kind of issues this might create. Let me know if you think I can help.
Paul
Paul,
I think you helped me out at the beginning of this project over a year ago!
My question to you is if you ever set a specific value in ultraware to tell the driver how "far" is one step (one step = 1.8 degrees)? I know how to set the follower ratio, but i'm not sure that will solve my problem.
What is happening is at a slow RPM i can almost count the steps as the servo rotates. The constant start-stop-start-stop of the stepped input seems too "coarse" . This causes bad vibrations at a higher RPM and faults out with a thermal overload.
I'm guessing that if I can set the driver to a much smaller increment per step, that the motion would be smoother. (i could be barking up the wrong tree as well).
Thanks again for the help!
-greg
Greg,
there is a menu called "follower" under "mode configuration"
There you will find a setting called Gear Ratio, Master:Follower.
I have this set to 1:4 for my application.
Also, under Encoders, there is a setting for the Auxiliary Encoder, lines per revolution.
I believe this is the step input you will use for the master. It might give you the
adjustment you are looking for.
Mine is set for:
Encoder ratio, Load:Motor 1:1
Type: Rotary
Lines per Revolution: 2000
I also wonder if the behavior would go a way if you tuned it a little less hot.
Good luck,
Paul
Paul,
Some success. I found a follower ratio that worked, but it's 1:540! Quite a bit different from your 1:4. Changing the Lines per Revolution didn't seem to affect anything that I could notice.
I have another question on your setup. Do you know what the max RPM is of your servos? I believe you said they are axis motors, so I'm guessing it's not too high. I'm getting violent vibrations above 400 RPM (below 400 is fairly smooth).
When I run the motor and set the velocity in Ultraware everything is great. I can run my spindle 2000 RPM smooth as silk. So I suspect it has to do with the stepped input signal. Someone had suggested that i need 1MHz minimum pulsing to get a smooth servo motion, but Mach 3 is limited to 45KHz. That makes me wonder if ANYBODY is running a servo spindle controlled directly from step/dir out of mach 3??????
Any thoughts?
Thanks again for your help.
Did you do any tuning?
You MUST!
An AB3000 will run smoothly with a step rate of only 1 Hz or less.
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