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Optocoupled driver boards Hello,
Has anyone used or had any experience with these stepper drivers?
What I'm looking for are detailed instructions on wiring or a really good diagram.
I have them wired in parallel, but I'm getting different voltage readings across each connection.
The website I purchased them from doesn't provide much help...
http://www.cncgeeker.com/
and I am not an electronics expert.
Thanks
Mark
I'm assuming you've downloaded and printed off the user manual from the site. Seems to me that's got everything you need in there.Originally Posted by alphamail
When you say 'wired' in parallel what are you wiring in parallel? the boards to the Power Supply, the motor windings, or what. Some clarification of your exact problem is needed. Where are you measuring the voltages?
Sorry about the photo quality-I had to use my webcam...
Yes, I have a printout of the Univelop 4 axis manual-
page 7,section 3.3, simply states"Connect suitable power supply at Input outlet on front of controller". That's it. No further instructions on wiring power to these controllers. No answers to my e-mails, either.
Basically I wired it up according to these layouts-
http://www.probotix.com/manuals/3Axi...tep_manual.htm
http://www.probotix.com/diagrams/3-a...ing_dia.v2.jpg
This was the most helpful diagram I could find, but may not be the answer.
Any help would be greatly appreciated.
Mark
Your wiring looks fine to me (see caveat later tho). That power supply is powering the motor circuits only (the +12v MOTOR circuit), however I dont see any wiring for the +7v (BOARD) circuit to each of the driver cards and the interface. Without that nothing will work!
As to the varying voltages, with the fuses removed you should get the same voltage at between the hot side of the fuse holder and GND. Measuring across the fuse-holder is meaningless...
To check the driver volts you need to measure between the +12v and the GND connection on each driver board. They should all be the same (try putting in one fuse at a time, power off between each measurement), however without the +7v rail being powered its anyones guess what state the driving transistors are in so I'd not power up the motor circuit at all until you have a suitable power supply wired up.
Back to the +12v wiring - I would keep the wiring from the Power supply to the fuse holder and ground block as short as possible and use thicker wire that that used for the motors themselves (or use two or three strands twisted together). This will reduce any interaction between the drivers. Remember those wires have to carry the combined current of all 3 motors.
Hope that helps...
Yes, the different voltages are due to your wiring. You've chained one after another. What you want is a star wiring set up. That is, a main buss with each fuse holder having it's own wire, not chained one after the other.
thanks for the info,guys,
irving2008,
So, should I have 2 wires running from each fuse holder, one to +12v and one to +7v, then run all the ground leads to the ground block?
I will be moving the fuse holders and and ground block, as all this will be mounted in a chassis.
MrWild
I've never seen a star wiring setup, - I will look into this as I originally thought some way of "splitting" the voltage was the answer. This may be it. Could you point me to a diagram of one?
Mark
Mr Wild: I don't think he has daisy-chained them. As far as I can see he has a common feed from the power supply (brown) chained to one side of the fuse holders and then an individual red wire from each holder to its respective driver board. The pink (?) common from the power supply goes to the ground block and then to each driver individually via a black wire. Therefore this is a star-wired configuration, is it not?
Mark: can you confirm my description above? As it is incredibly bad practice to refer to variable voltage power rails by their minimum voltage and not their function, not to say confusing, I will use BOARD (+7) and MOTOR(+12) from now on. The BOARD supply should be a different supply from the MOTOR supply - because the MOTOR supply will see large transient voltages from the back-emf of the motors which will exceed the BOARD supply maximum rating. NOTE that the interface board must use the BOARD supply not the MOTOR supply.
What voltage is your MOTOR power supply and what is its maximum current rating? According to the specs the MOTOR supply can be between 12 and 36v (but I'd keep it as high as possible for stepper performance, but below 32v because of the transients mentioned before). The BOARD supply however is 7 to 12v, nominally 9v (this is because there is almost certainly a 5v regulator on each board - for minimum heat dissipation err towards 7v rather than the 12v), so you need to source a 9v supply capable of supplying 1A max although you'd probably get away with 800mA as its unlikely all the boards are worst case consumption. Radioshack have a 9v 800mA wall-wart that is suitable at $19. The positive side of this will need to be wired to each board's BOARD input (and the +7 input on the interface board). The GND for each of these should be wired back to another GND block and then to the new supply negative side. Do not rely on the existing MOTOR GND connections.
Irving2008,
Yes, it's wired as you describe.So, I suppose it is a star configuration.
These are the specs for the motor power supply-
Input: 100-120V 4A
200-240V 2.3A
Output: 24Vdc 6.5A
150W switching power supply.
Adjustable voltage output.
Take a look at the attached diagram. Is this the wiring setup you described? I used yellow/blue wiring for the positive/negative of the board supply to aviod confusion.
thanks
Mark
Yep, I'd say thats exactly right. One comment tho, keep the MOTOR GND (black) wires as short as the red ones rather than running them round the outside. You should keep all the power wiring as short as you can.
Thanks,
This really helps.
I will be mounting all this in a chassis,and I will turn the cards around so they will face the fuse holders, reducing the power connections to about 2 or 3 inches.
Mark
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