You are correct - it's as simple as you said. I don't know about the S7. I'm an electronics guy. Try a transistor output module first. Connect the pulse to the common of the 8 transistors. Wire each output to the Clock input of the Stepper Driver module. You might need a module rated for 5 volts, not 24. The limitation will be transistor switching speed. Try it to see how fast you can run before you start missing pulses.sie625 said:The motors and drives i was looking at were from Haydon, but that was really only a result of finding them first. Recommendations would be appreciated. Ill probably need like a size 17.
After looking into this more it seems like all i really need to make motion happen are step/direction inputs. As i mentioned before, there is not very much travel involved, and speed is really not an issue, so i dont think i need any acceleration ramps or anything like that. I also found that the S7 has a Pulse output. So here is my question/possible solution, i hope that it is not too misguided. Can i use the pulse output to control all 8 motors? Can this be done using a "multiplexer" as was suggested above? I am also not familiar with that, so some guidance or a recommendation would help. Would this be similar to putting the pulse to 8 relays and then just switching on the relay for whichever motor i want to move?
the way i was thinking, i would need one pulse output going to 8 relays, 8 outputs to control the relays, 8 outputs to control "direction" of the motor. This seems pretty crude to me, but as i mentioned, speed isnt an issue, so whatever i set the frequency at would be fine for all 8 motors and across the entire travel.
am i getting closer?
The multiplexer is an IC. I don't know if there's any off-the-shelf types. This is a solid-state version of 8 small relays wired in a 1-of-8 configuration.
Use another set of 8 transistor outputs to drive the direction command.
Use NPN if the module has active low inputs.
If you trust your mechanical operation, encoders may not be needed. "Home" the motors with a home sensor, then use an up/down counter to remember position. Use the same pulse output to run the counter.
Try this with 1 motor, then 2 motors. If you can't get it to work, then buying smart controllers is the way to go.
The accuracy is based on pulses per revolution of the stepper motor, and the pitch of the lead screw. The typical stepper motor will be 200 pulses per revolution, 400 with half stepping. Minimum accuracy is +/- 1 motor step. For 1/16" inch, I would try for 4 times that, or 1/64" per step maximum.
It's easy to undersize steppers. Leave room for size 23.
Use stepper motors with integrated drive electronics. Many have a microstepping option.
Take a serious look at Baldor's website for more info, and a complete range of options.
http://www.baldor.com/pdf/literature/BR1202-C_NextMove.pdf
Let me know if you need more info on the multiplexer idea.
Keith