RJ45 NEMA 17 Adapter

Morning all,

I've been working on a project recently to develop a shield for RAMPS 1.4 which converts nearly all connections to CAT5 (exceptions being hotbed / hotbed thermistor). One component of this development are the adapters which would allow the conversion of my NEMA 17 steppers to CAT5 cabling (conductors in the CAT5 cable will be paired to allow up to 1A per wire to the steppers). I've been working on a small PCB with the appropriate pins and RJ45 connectors so no surprises there.

I do have a question, however, on the best approach for indicating whether the motor is energized or not. I like the idea of being able to tell when any of my steppers are powered up (call it my idle curiosity). From my understanding (if you can call it that) of 4 wire stepper motor operation is that each pair (1A/1B, 2A/2B ) vary between +/- during each 1.8 degree step. Obviously this doesn't work well for powering an LED so I am thinking about adding a bridge rectifier to each pair which, theoretically, normalize the current direction. The only reason I'm showing two LED's is that I want to keep current draws on each pair the same so as not to put any undue strain on the motor or controller. The current draw of the LED's is very low (20mA) so I don't think the stepper controllers will notice them.

Would any of the electrically inclined individuals out there be able to comment on the layout and if there are any pitfalls I haven't considered? I'm an architect by trade so I only have a cursory understanding of circuit design and would love some input.

As the development of the RAMPS shield continues I'll post updates.

Thanks,

You might want to have a look at Generation 3 Electronics. This design was the de-facto standard for quite a while and used RJ-45 connectors a lot.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

I know it's been a while, but did you ever get anywhere with this design?