Centroid Community CNC Support Forum

Gentlemen,
I've really tried to find the answer to this question in the schematics and the forums.
I'm trying to connect Acorn to The Ahha! motor driver boards, via the DB25 connector on the Acorn board.

All of the Acorn to Whatever schematics I've looked at show a +5Volt connection to the "common" terminal of the drive board.

My Ahha! documentation specifies that the ground pins of the Ahha! inputs are tied directly to chassis ground. There is no "common" terminal that could be connected to +5 volts. That documentation further states "DO NOT CONNECT ANY EXTERNAL POWER TO ANY INPUT OR OUTPUT"

I'm VERY reluctant to just try connecting the +5 volts to the Ahha! "ground" terminal. Do I need to do something more elaborate in this case to make this connection safely?

A schematic showing what I have to do would help a lot.

Thanks for any assistance!
Ron K

Hi Ron, if you want better help please post a link to the manual for your drives. With out a manual we really can't answer your question. I personally have never heard of that driver so a manual would be super helpful. If the driver accepts step and direction signals it should be easy to hook up.

Gents,
I purchased the Ahha! cnc control package in about 1995. It worked ok on 4 machines until the hard drives crashed. This setup was on the Do Not Resuscitate list, and I would like to retain just the motors and axis drives.
Ahha went out of business long ago, and they never had any internet presence that I know of.

I've scanned the hardware manual and attached it to this post. I also have the software manual, but that is huge and I'm not going to scan the whole thing. If I need to upload anything more to make this easier, I will do my best.

I think page 18 has the information regarding step and direction connections.

I really appreciate any assistance.
Ron

Not sure what kind of machine this is but it's simply not worth saving those drives and motors. They are just too old and no longer efficient or even supported by anyone. Drives and motors are so cheap these days and they have modern electronics and feature you'll never have on those old drives.

You are right, those drives and motors should have a DNR signed and hanging from their hospice bed.

ShawnM,
At the moment, I'm broke. I don't have the energy or money to upgrade now. If I can make the step and direction connections, I'm sure it will work as well as it did back in the day. Not great, but way better than manual.
I'd like to be able to use the cnc to make new motor mounts, among other things. The machine is a series 1 Bridgeport with ball screws. I built it with z moving the knee so I can still use the quill. I did some incredible and complex things with that machine.
Any help is appreciated.
Ron

Gentlemen,
I'm still struggling with this.
I still have a CNC running the Ahha! hardware and software, and the machine moves on three axis just fine. Rapids on the order of about 60ipm. Open loop steppers, step and direction motor drives from Ahha!. That gives me reason to believe that if I can get the centroid step and direction inputs to work with the Ahha! drives I will be able to do CNC stuff. The machine I'm trying to get moving is the second of three machines. eventually I'd like to convert at least 2 of the 3 to Centroid.
The Ahha! drives want 5volt step and direction inputs. I'm just lost on where to connect the 5V in the connections between the Centroid outputs and the Ahha! input.
If one of you folks could look at the hardware manual I attached in previous post, I'm sure you can direct me.
Thanks for any assistance.
Ron

Due to the age of those drives there is no guarantee that they will work properly when connected to a modern controller. That said, after looking over the provided manual, all the info for connection, including the use of pull up resistors is in there. Connect to the step/direction pins and common on the db25. If it works, good. If not, then it won't work.

BTW, isn't asking the same question over and over and expecting a different answer the definition of something?

Here's the pinout for the DB25 on Acorn H6 for connecting 5V step and direction signals.

i moved this thread into the Acorn forum

Gentlemen,
I know it's been a while, but I wanted to post an update.
I got the Centroid talking to the Ahha! I get good repeatability and no lost steps. Rapid travels (when the machine is actually warm like 60F) of 60 ipm X and Y, 40 on Z (I move the knee).

Nobody responded to my request for assistance with a schematic, but one generous fellow did mention 5 volt pullup resistor. That led to a search online and youtube videos with diagrams and explanations. So Thank you.

I'm attaching a schematic which show how I wired up the pull up resistor. I still had to ground the enable axis pin on the Ahha! driver to get motion.

I found information on parameter 968: step and direction frequency. I set it to 40000Hz max, but the Wizard changes it back to 200000. (The Ahha! seems to work fine with the frequency set to 200000). I believe the Ahha drives are speced to work at 45kHz max.

I'll be glad to help anyone trying to make this work.

Ron (rknit@yahoo dot com)