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  #31  
Old Mon 22 October 2007, 12:04
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Mike, while it won't work, it shouldn't cause any damage? I think that Hugo is worried that he may have cooked something.
  #32  
Old Mon 22 October 2007, 13:13
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
I asked Steve Stallings of PMDX about mixing drives on the PMDX-122. Here is his reply:

Because the PMDX-122 does not have opto-isolation (to the drives)
and thus separate grounds, you can use any GND terminal
or any +5 AUX terminal to feed the common of a Gecko
drive connected to the PMDX-122. The COM terminals
on J1 - J4 and the jumper JP1 are just a convenience,
there is nothing magic about the COM terminal on these
connectors.
  #33  
Old Mon 22 October 2007, 13:33
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Gerald, Hugo,
There should not be any damage to the circuit. What happens when the circuit is working properly is that there are a few milliamps of current going through an LED. In order to work, the Anode end of the LED is connected to a higher voltage and the Cathode end of the LED is connected to a lower voltage. In the case of the G202, the Anode end of the LED is connected to +5 volts and the cathode end of the diode is connected to a signal line. When the signal line goes LOW (near ground), current passes through the LED and the LED lights up. In the case of the G203v, the Cathode end of the LED is connected to GROUND and the Anode is connected to the signal line. When the signal line goes HIGH, current flows through the LED and the LED lights up. In either case, the amount of current going through the LED is limited to a safe level by a resistor. The JP1 jumper on the PMDX-122 determines whether the Anode is connected to +5V or the Cathode is connected to GROUND.

One of the functions of a diode (like the diodes in a bridge rectifier that we use to convert AC to DC) is to block current. So, in most cases, when an LED is connected backwards, no current can flow through the device and the LED will never light up. The exception would be if we connected an LED to higher voltage than it was designed to handle. In that case, the LED could be destroyed; however, a Break Out Board only uses 5VDC on its signal lines, so no damage will occur.

Because I have both G202 and G203v stepper drivers, I have often forgotten to move the JP1 jumper when I've connected different devices to the PMDX-122 board. In every case, as soon as I moved the jumper to the correct position, everything worked properly.
  #34  
Old Tue 23 October 2007, 09:00
Hugo Carradini
Just call me: Hugo
 
Pto. Ordaz
Venezuela
Thanks Gerald for your interest in helping .
Mike, is a pleasure reading your comments. I am really learning more of my electronics (the heart of the baby beast)then if I had not go through these problem so I am glad with the situation. I heard of so many cases that is just a simple thing what is wrong that I am sure this is one of those situations. These baby beast show me how strong and precise she is so I have to learn more, how to take complete care of her.
  #35  
Old Thu 03 January 2008, 14:22
Pilar
Just call me: Marcos
 
Sao Paulo
Brazil
What is the best drive to start a machine G203V or g202 or others?
I pretend to use G-Rex G100 / drive g202 / and motor Phase Stepping Motor
- PK296A1A-SG7.2 2-Phase Stepping Motor . Any sugestion, idea etc? sorry of my English.
Thanks,
Marcos Pilar
Brazil
  #36  
Old Thu 03 January 2008, 15:36
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Marcos,
The stepper motor determines the stepper drive that is best for you. If you already have PK296A1A-SG7.2 stepper motors, then the "best" stepper driver for that motor would be the G202. That is because that motor has high inductance and the G202 is better suited for that motor. If you have not already bought your motors, I would suggest the PK296A2A-SG7.2 motors, the G203v stepper drives and the PMDX-122 breakout board.

The PMDX-122 is a very good breakout board if you're using a parallel port. There are many other good breakout boards that others prefer. I've only used the PMDX in my testing. The G100 is being discontinued. I have a G100 and also a G101/G102. They are excellent devices, but Art and Steve (at Artisoft) have had serious difficulties making the G100 work as well as they had hoped. However, they are working with other devices that should give us most of the good features of the G100 without the expense or the difficulty.

The power supply that you use will depend on the motors that you select. The PK296A1A-SG7.2 wired either bipolar series or half-coil can use a 70VDC power supply. The PK296A2A-SG7.2 motor would use a 30V to 35V power supply if you wire it half-coil or a 50V to 70V power supply if you wire it bipolar series. (I prefer half-coil, but either will work.)
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