Newbie- Convert/Retrofit old Precix HPGL controller to G-code

[TAProwler]

OK - Pics 5_driver.jpg and 6_driver.jpg shows what I was looking for. The old control board ("HPGL BOB" for lack of a better term) is using terminals 2,3,4 & 5. Using the info from the driver im804.pdf file you posted earlier, it looks like these represent (for each axis):

Term 2-Step Clock (STEP signal from new BOB gets connected here);

Term 3 - Direction (DIR signal from new BOB gets connected here);

Term 4 - Opto Supply (Not completely sure what this is, but I suspect it is a +5Vdc supply to power the opto couplers that are part of the optical isoloation system. Leave it connected as is from the HPGL control board).

Term 5 - Enable (ENABLE signal from new BOB gets connected here)

So, from here you need to:

1 - Take more pics of current connections and/or label the wires as they are currently connected (so you can put it all back together to original condition if you ever need to in the future).

2- Remove the wires from all the terminals 2, 3 & 5 on each of the three stepper driver boards (they look like white[or maybe yellow], green and black).

3- Get/buy new BOB, mount it somewhere, and connect the outputs from each of the X, Y and Z axis outputs (STEP, DIR, and ENable) to the appropriate terminals of the X, Y and Z stepper driver card as outlined above.

I would recommend the BOB from Tom at CandCNC. I have bought his products in the past and they are good products. Tom is a very smart guy and he does a great job of supporting his products. I did a similar mod to a Torchmate TM1 CNC table using his products to add automatic torch height control to the table (for a plasma torch). The table/system works great. I also hacked Torchmate's stepper driver cards and motor power supply to use the CandCNC BOB etc (similar to what we are doing here). That's how I know what to do with your system to get it to work with a PC and Mach3.

This should be a very straight forward mod for you that is not hugely expensive.
Have fun.
Regards, Todd

[adirondack cncr]

well we decided to go with a board from cnc4pc (C35 - QUICK SETUP BREAKOUT BOARD) wired it up but when i try to move anything with mach3 i cant get anything to move. im not sure if it is wired right or if we did not configuring it correctly , we are new to mach3. will post the manual for the break out board and my stepper drivers. Also a x-reference pic of how we wired it. where should i start trouble shooting. thanks for the suggestion TAProwler but i couldnt use the hpgl board any more so i tried using 5v from the new board but i dont know if this is going to work.
thanks shad

[TAProwler]

Nice Job, So Far Adirondack,

Well, it looks like you have the correct Parallel Port pins programmed into Mach. That's a good start.

The first thing I noticed is (I was unable to find in the BOB manual) what exactly RJ45 Pin 2 and pin 6 is for (left hand column of your pin map from the BOB manual). Is it a STEP signal, or the DIR signal?? It looks like you've mapped 2,4,& 6 as the STEP signals (these go to pin 2 of each axis RJ45 connector) and you've mapped 3,5 & 7 as the DIR signal (going to pin 6 of each axis RJ45 connector). Unless I missed it in the manual, these could be reversed!? You have a 50/50 chance that it is correct as it is now. Do you have a clarification on that, maybe? A quick call to CNC4PC would clear that up.

My next thought is - what have you done with the ENABLE signal for the new BOB (see para 5.2 in the BOB manual)? That swithch that they show there is what you will eventually will want to be for your E-stop system. But, for now, you can just tie it (jumper it) to +5V to ensure operation of the BOB itself.

The third (and fouth) problem might be the acitve high or active low of both the STEP and DIR signals out of Mach (columns to the right of your mapped pin settings in the screen shot that you posted). Those can just be swapped easily and tried to find the setting that works.

BUT FIRST - Here's how I would start to troubleshoot this system:
1. Start with just 1 axis at a time, let's say the X axis.
2. Unplug all of your RJ45 connectors to all of your stepper driver cards.
3. Turn on the BOB and then start Mach.

4. Does the BOB power up? Do you see the power light? See any flashes on the Status LED lights?
4A. If not, check power to the BOB. Check that the BOB is enabled. Try to find out why the power LED is not lighting up.
4B. If yes, the BOB is powered, then move on to the next step;

5. Plug in just the X axis RJ45 connector and try to get Mach to jog the X stepper.
5A. Does the motor move at all? Does it hum? If yes, then the issue is probably a motor tuning issue. We'll cover that in a future post.
5B. If the motor doesn't move or do anything at all, then one at a time, change the step dir act high/low in the Mach config menu (change red X to green check mark)and re-try moving the X motor. If nothing happens changing them one at a time, then try to change both to green checkmarks. Some combination should bring the motor to do something. (However, this also assumes that the stepper driver is wired up correctly - which it should be.)

6. If none of this works, find out for sure what pins 2&6 do on the RJ45 axis connectors and remap the Mach config as necessary. Then re-try the above steps. If you are trying to put a DIR signal on the STEP input (and vice-versa) you wont get proper operation - obviously.

7. If you are still not getting any movement, then that opto supply might need investigation. Or, more troubleshooting from the stepper driver to the motor. We'll see.

8. Steppers are pretty forgiving motors. If you find yourself trying to jog a motor and it makes a loud screeching, buzzing, or howling sound - it's probably won't do the motor any harm for short periods. I mention this, because if the motor tuning is way off (at first) when you do get your motors to move, they may move really slow, really fast, or stall and howl. Don't be too alarmed. If you have your system on for a long time and the motors get really hot - that is a bad sign. But that has more to do with how the motors are wired to the specific stepper driver - which you have not changed, so it should be good.

Try this stuff and let me know what you find out. Also, if you can, please post a pic of your BOB as you have it wired now. It just helps to catch simple stuff if you can look at it and see things, sometimes.

One more thing. If you are not familiar with it, look in the Mach manual and start getting familiar with motor tuning. Eventually you will have to deal with this when you do get your motors moving.

Happy troubleshooting. Ain't this CNC stuff fun?
Regards,
Todd

[adirondack cncr]

thanks TAProwler i appreciate the help.

the bob has power and there are several lights on. i have the enable powered through an e stop switch. The power light is on and the output light is lit. there are a couple of other lights lit next to some power outputs. i have some limit switches hoked up and when they are triggered i can see them with mach in the diagnostics screen. i have them set up as homing switches. in the diagnostics on the port 1 pins current state screen i have only two squares lit up green (believe these are related to limit switches since when i trigger them the green flashes) should i see more like ones for step, dir, enable?

i did try changing step and dir low active with different combinations but nothing seemed to make the steppers move. We did get one to move by accident while we were checking to see if we had continuity from the parallel cable where it plugs into the computer to where the wire is hooked to the stepper driver. we where testing pin 2 which we had set up for step. we only did it briefly since it was rather glitchy and uncontrollable, it kind of spit and sputtered. im just a little curious what to check for on the step and direction pins, from what i gather it is continually changing in voltage so would you need an oscilloscope maybe? oh yeah the steppers are in a holding position all the time the unit has power but i assume this is from the stepper power supply always having power. is this normal? should i try to use an output from the bob to power the relay for the stepper power supplys? If i remember right, when we first got the router and it was in the mood to work , the steppers did not hold and you could push the gantry around until you jogged it. Then while it was moving you couldnt stop it if you tried pushing against it. This didnt seem right but maybe im wrong. I wood assume that it would have holding power unless it was moving..??

i did not have my camera with me so i will post some pics tomorrow. i will try to gather the info for motor tuning maybe we miscalculated our steps. we were thinking about trying a different board .(even thought its probably something simple we are just overlooking)

[TAProwler]

Originally Posted by adirondack cncr the bob has power and there are several lights on. i have the enable powered through an e stop switch. The power light is on and the output light is lit. there are a couple of other lights lit next to some power outputs.

That's good. Now we know for sure the BOB is powered, etc.

Originally Posted by adirondack cncr i have some limit switches hoked up and when they are triggered i can see them with mach in the diagnostics screen. i have them set up as homing switches. in the diagnostics on the port 1 pins current state screen i have only two squares lit up green (believe these are related to limit switches since when i trigger them the green flashes)

I believe that is right/normal - but I haven't opened Mach in a very long time. Maybe someone with more Mach experience can answer this one.

Originally Posted by adirondack cncr should i see more like ones for step, dir, enable?

I think you should be able to - but again, someone with more knowledge of Mach might be more help here.

Originally Posted by adirondack cncr i did try changing step and dir low active with different combinations but nothing seemed to make the steppers move. We did get one to move by accident while we were checking to see if we had continuity from the parallel cable where it plugs into the computer to where the wire is hooked to the stepper driver. we where testing pin 2 which we had set up for step.

That is a good sign. What was happening was the STEP input to the stepper driver was picking up the on/off of voltage you were using to test the cable as a "step signal" and trying to move the motor. When Mach wants a stepper motor to move 1 step, it sends a single voltage pulse out on the #2 pin. That pulse can be an always "low" signal that steps "high" for a short time, or it can be the opposite where the output is always "high" and the signal to move is a short pulse to a "low" state. This is what you were changing with the Dir Active High/Low and the STEP Active High/Low. You have to set it to what your stepper drivers are designed to "look for."

Originally Posted by adirondack cncr we only did it briefly since it was rather glitchy and uncontrollable, it kind of spit and sputtered. im just a little curious what to check for on the step and direction pins, from what i gather it is continually changing in voltage so would you need an oscilloscope maybe?

That is because as you are touching the power to the connector/terminal there is a period of time where the voltage goes up/down very irratically and quickly. Same thing happens as you try to break a connection. The stepper driver "sees" these as step signals. Yes, you could set up an oscilliscope to watch these signals. The are square waveforms as I described above.

Originally Posted by adirondack cncr oh yeah the steppers are in a holding position all the time the unit has power but i assume this is from the stepper power supply always having power. is this normal?

Yes, it is. When you have your motor power supplies on and there are no step signals present there is a "holding" current that is going thru each stepper. When a step signal is recieved, the stepper driver sends the appropriate power signal (from the individual power supplies) to the stepper motor to move it one step. Then it should lock in position again.

Originally Posted by adirondack cncr should i try to use an output from the bob to power the relay for the stepper power supplys?

No, I would leave it all as it was originally designed by the table manufacturer. All you want to do is put STEP and DIR signals into the stepper driver inputs from a different BOB. Leave everything from that point to the motors as it was orignally designed.

Originally Posted by adirondack cncr If i remember right, when we first got the router and it was in the mood to work , the steppers did not hold and you could push the gantry around until you jogged it. Then while it was moving you couldnt stop it if you tried pushing against it. This didnt seem right but maybe im wrong. I wood assume that it would have holding power unless it was moving..??

That does seems wrong. Typically, a table that is "ON" will have all of the steppers holding when no signal is applied. You should feel resistance and it should take a lot of power to overpower the steppers to move the gantry or carraige - but you can do it. The steppers will just "skip". When this happens and you don't want it to, they are called "missed steps," or it is said that the table/system is "missing steps." This can cause a lot of problems when you are trying to cut accturate parts. The condition is usually caused by mechanical binding, friction, or something else not being set up right.

At this point, it appears that your step signals are getting thru to the stepper drivers and are able to (albeit crudely) move the motors. It seems to me like the signals are not being genereated by the BOB or Mach. So, we should start looking for causes in the BOB or (more likely) configuration and set-up in Mach.

Unfortunately, my Mach skills are not up to speed. I haven't played with Mach in a really long time. I do remember a couple of things though.

Since the STEP/DIR Step Active High/Low didn't seem to make a difference - I would set them back to Step Active High.

Somewhere in Mach is a setting to change the length of the STEP and DIR pulses. I think it is in the motor tuning section. Try changing the pulse length to a little longer. If it is too short, the stepper drivers maybe be missing them by mistaking them for noise.

Investigate the Mach Charge Pump system and make sure that the BOB is doing what Mach needs it to do - if anything. The Mach Charge Pump system will not let any signals go, if the BOB is not "ready". It's designed this way to make sure that there are not unexpected movements of the table when starting up, etc. This may be inhibiting the motor movement.

Take off all of your limit and/or homing switch inputs to the BOB for right now. You can hook all that back up and test it all once you get the motors moving satisfactorily. Right now, it just eliminates one possible area that might be inhibiiting motor movement.

Oh, one last thing - not related to the BOB or Mach. Check to make sure that the power supplies are all powered and that each stepper driver is getting that power (voltage) delievered correctly to each input on the stepper driver card. Check the voltage of the power supplies on the appropriate pin of the stepper driver card (connector P2 and Pin 4).

Happy hunting. Let us know what you find out.
Regards,
Todd

[adirondack cncr]

well we ordered another new bob, changed it and it worked right off. we did a little motor tuning and everything seems to be working. we even did a few test cuts. had a little trouble with limit switches and mach, we changed the debounce setting and so far so good. thanks TAProwler for all your help we appreciate it alot.
thanks again
shad

[TAProwler]

Alright Shad! Nice job.
I'm glad it's working for you.
Thanks for the update.
Happy cutting.
R/ Todd