witch bob
 

I would like to know my most of you the PMD over the CandCNC?

Mac

Because we have good experience with it, no complaints, good docs, good support, good price.

Mike,

Thanks for the info

Gerald you had mentioned the PMDX-125 awhile back and I was just checking it out. Does anyone know of any mechmate builders/members with it running? Looks very promising! Still as you said, would be good to wait and see, let them debug everything. Don't like being a guinea pig while cutting!

Under the assumption that the board had been around for a while now, I got the PMDX-125 Gecko 203v bundle from PMD and am now assembling a kitchen table experiment (waiting for motors to arrive). Hoping some one has by now tread this path and is willing to share some tips.

I'm not too stressed about frying the Geckos (internally fused), and think I can hook up the BOB (even though it is 240v at one end - more than I like in live circuits), but I'd love some pointers on wiring the estop and Gecko fault detection and, especially, some of the silly things to avoid with this particular setup.

PS one of the nice things is that the parallel port ground and output ground are ( optically? wtm) separated

A reversed supply polarity still fries them, fuse or not, I am told.....

The 203's are pretty indestructible, reverse polarity will fry the internal fuse (a 15A part), replacement is bit of pain if you have mounted them in the enclosure already. Spare fuses are available from Gecko or Digikey, I don't have the part number handy.
Greg

See this post on the Gecko yahoo forum, where a G203 owner sent it in for repair and got warned that reversed polarity can damage the drive.

Following on from CNCB's post

Has anyone tried these yet as I am about to place an order for BOB and drivers.

All help and recomendations greatly appreciated.

Cheers
Peter

I purchased one and I'm on my way of building the control box, I already built a control box with the 122 (not mechmate related)
Most of the help you will find here in the forum is for the 122, if you feel confident about interpreting the manual I would go 125, otherwise 122.

Pete, almost all BOB of different make using parallel port can be use. You just need to do enough research...

The main function of a Break-Out-Board is to amplify (and protect) the parallel port signals. I use the PMDX-122. It is an excellent board, but there is no reason that you couldn't build your own, if buget is a main consideration and time is not a factor. A single chip can handle all the step and direction signals for a 4-motor machine. Another chip can handle all the input signals and a third chip can handle the output signals.

The Geckodrive G201, the G201X, the G202 and G203v stepper drivers (most commonly used) all have built in opto-isolation. You would need to add opto-isolation to the input signals and the other output signals, but each 4N2x chip costs about $0.25 each. Add a wall-wart type 9VDC transformer and an on-board 7805 voltage regulator and you would have your own break-out-board.

Building wire-wrapped boards is no longer "fun" for me. I either design boards and then have the boards made (at several hundred dollars for the inital prototype) or I buy ready-build boards (like the PMDX-122 for about $90). But, if you're in for a little design work and a little excitement, build your own. For some, it is part of the experience of building a machine.

If you can design PCB, you can also cut out PCB with MM... or wash your own PCB with conventional method.

Hi Mike,
I had to look up opto-isloation and I found it is a way of transmitting a signal while keeping circuits electrically separated.

I remember there were discussions about the computer ground needing to be separate, so I guess this is the reason the PMDX125 the parallel port ground and output ground are alledgedly optically separated. I'm guessing then that I need to keep the parallel cable isolated from the case if I earth the BOB to the case?

The opto-insolator is use to as the name implies, isolate the source & load, in this case the signal from the PC to the driver in the event of overloading or short circuits... etc. not really about the grounding...

Red,
Ken is right about opto-isolators. Their purpose is to keep the electrical noise that is generated outside the control box from entering the control box and messing with your computer.

It is good practice to ground ALL D.C. signals to a common ground lug, including those that are opto-isolated.

An opto-isolator is an inexpensive device that is commonly used to translate different voltages. For example, I use 12VDC proximity sensors. One side of the opto-isolator is connected to the 12V equipment. The other side of the opto-isolator is connected to the 5V controller side. Only light passes between the 12V and the 5V devices. (That's the 'opto' in opto-isolator.)

Opto-isolators are also commonly used to isolate any signal outside a process control computer's box from the process control computer's circuits, even when the voltages are the same. The cables that connect the control box to the machine sometimes act like antennas and collect all kinds of noisy garbage. Putting an opto-isolator between the inside world and the outside world keeps the 'garbage' out. (Sorry for the metaphor, I know that Gerald's livelyhood depends on 'garbage', but electrical 'garbage' is really nasty stuff.)

Because opto-isolators are usually slow to change state (1 to 10 milliseconds), fast acting electrical noise is too short in duration to activate the signal. Also, because the input L.E.D. inside an opto-isolator requires current to 'turn on', most noise lacks the 5mA to 10mA required to light up the L.E.D.

On my Shopbot, when I installed opto-isolators on the input lines, ALL of the communication errors disappeared. The parts cost less than $10. The result was priceless.

My students are back at uni this week with a ton of learning ahead of them ... I know how they feel!
Thanks for the clear explanation. I have a much better handle on where to apply opto-isolators now.

correct color wire
 

Hi i need of your suggestion, i have this stepper motore nema 34 there are 8 wire, what are the correct 4 wire color for gecko g203v and where i have to connect to geckos ? For example yellow to phase A ect. thanks

i forgot to upload pictures sorry

The M1343020 motor has eight leads, which means that it has four coils. Coil A1 has the Red and the Yellow leads. Coil A2 has the Blue and the Black leads. Coil B1 has the White and the Orange leads. Coil B2 has the Brown and the Green leads.

To wire the motor half-coil, connect the Red wire to terminal 3 on the G203v (Coil A). Connect the Yellow wire to terminal 4 (Coil /A). Connect the White wire to terminal 5 (Coil B). Connect the Orange wire to terminal 6 (Coil /B).

To wire the motor bipolar parallel, connect the Red wire and the Blue wire to terminal 3. Connect the Yellow wire and the Black wire to terminal 4. Connect the White wire and the Brown wire to terminal 5. Connect the Orange wire and the Green wire to terminal 6.

The motor has 1.5mH inductance per coil, so I would use a 35VDC power supply.

The motor is rated 5.6A, but it doesn't say whether that rating is for unipolar or bipolar parallel. I'm guessing bipolar parallel. You would use up to a 188k current limiting resistor. For half-coil (if I'm correct about current drawn by the motor), the motor would draw about 4A, so you would use up to a 62k resistor. Watch the motor's temperature. If the motor gets too hot, use a resistor with a LOWER value.

------------------------------------------------------------
I thinking use unipolar mode 4 leads, i just bought resistor 200K on Gecko G203V i send you in attachement some pictures,
toroidal is 230V /50 HZ - 500VA
1 out 25V /20A
1 out 9V /1A
you can see others components
Could you check my pictures searching errors?
Under geckos driver there are 2 propeller fan
For finish machine i needs of emergency stop - pause - and start button
the right wiring to stepper motor to G203V
are:
RED TO PHASE A
YELLOW TO PHASE A-
WHITE TO PHASE B
ORANGE TO PHASE B-
CORRECT?
Thanks so much i hope to finish machine next mounth
unfortunately I do not understand electronics

You have correctly matched the motor's wires to the proper terminals on the G203v.

Because you have wired the motors half-coil (instead of bipolar parallel), you should use a lower value resistor. Instead of using a 200k resistor, try a 47k to 63k resistor. 47k is popular, so it should be easy to find.

You are daisy-chaining the power connections to the G203v. Instead of daisy-chaining the conntections, you should use a Star connection method. That means that all of the G203v Power + connections are directly connected to the power supply's (+) connector and that all of the G203v Power (-) connections are directly connected to the power supply's (-) connector. (I use a terminal block with jumpers to make that connection simpler.)

Pay close attention to your wire colors. The Yellow/Green color of the ground wire usually indicates that that conductor is AC Ground. When I use "standard" wire, I put a 1/2-inch length of colored heat shrink tubing close to the connection point. The color of the tubing indicates the conductor's function and/or voltage.

You're doing a very fine job of construction. Everything is neatly laid out. It's obvious that you're being very careful. Keep up the good work.

What is the correct method to working stepper motor ? unipolar or bipolar? I read the post uncorrect forum ? In your machine which kind of wiring have you 4 leads or 8 leads? Unipolar or bipolar
thanks, i hope to solve problems, i have fear to make irreparable errors

Renraku, forget about unipolar; it doesn't apply to the Gecko drives. A unipolar drive uses 6 wires, not 4. The correct method is the method that matches the drive you have, which is bipolar in this case.

The choice you have to make is bipolar parallel, bipolar series, or bipolar half-coil. You probably don't want to use bipolar series, so that leaves the two options Mike pointed out. Your proposed wiring is bipolar half-coil, which will work just fine with the 47k resistor he stated.

8 wire motors exist because you can choose how you want to use the motor; they can be wired to be driven in any unipolar or bipolar configuration. Nobody has a machine with 8 leads, though; they have either 4 leads for bipolar, or 6 leads for unipolar. You then set the motor up accordingly.

Not is important for me methot unipolar or bipolar, just that it works well, ok, can you tell me what leads color i have to connect to geckos G203V and where, for example yellow to phase A etc. problem is: i don't know how connect stepper motor to the gecko, and i don't remember which post talking about a mathematical formula for resistor and total was 188K
This thing is setting a nightmare for me, wires, calculations do not want to think about how I set mach3 or I go crazy
thanks so much

Renraku, as per the above:

RED TO PHASE A
YELLOW TO PHASE A-
WHITE TO PHASE B
ORANGE TO PHASE B-

and a 47k resistor.

thanks

Renraku,

Start simple. Connect only one G203v. Connect only one motor. Configure Mach 3 as that the one motor is connected to the X-axis. Experiment until you understand how to drive that one motor properly. Take lots of notes. See what happens when you connect Red to Phase A and Yellow to Phase /A, White TO Phase B and Orange to Phase /B. Then see what happens when you connect Yellow to A and Red to /A OR Orange to Phase B and White to Phase /B.

Don't rush.

Work slowly until you understand how to wire the motor and how to configure Mach 3.

If you can, use a 22k resistor for current limiting for a few hours. See how hot the motor gets when you run it at different speeds. Then, try a 47k resistor for a few hours. The motor will run much hotter, but it will also be able to move a bigger load.

Experiment carefully until you understand how the system works. Be sure to turn off the power each time you rewire anything.

That's the method that I followed when I tested a lot of different components. I started with one motor and changed things with that one motor until I understood how everything worked. It took time, but now I know what happens when I change the voltage, when I change the current available to the motor, when I change the leads of the motor, when I change the configuration in Mach 3. Now I know how fast I can run a motor. Now I know what happens when I change the acceleration (ramping) in Mach 3.

Everyone of us had to start at the beginning. There is a lot of information on the forum, but, if you're like me, you'll understand things better if you take the time to experiment for a few hours.

Thanks so much Richards, i'll do it, but it's all complicated to understanding for me, I hope to do no harm

I Richards, i've changed each wiring directly from Geckos to PMDX-135, and i've changed the resistors from 200K each to 47K each, is it better and correct? I send pictures by attachment, if is it correct could i try to connect to stepper motor and try to move the axis, and see if the machine works? Other question about bridge of motherboard PMDX-122: it's like i received it, i have to move some bridge or is ok ?
Thanks so much