On 17 September 2013 04:08, Gregg Eshelman <[email protected]> wrote:
> Got my motors, drives, power supplies and BOB today - without any wiring 
> diagrams. Some searching brings forth sort-of diagrams but they show only one 
> wire each for pulse/step and direction to the BOB, the drives have + and - 
> for each.

The BoB has a row of opto-isolators, so step 1 is probably to work out
if they are wired to 5V with the parport on the low side, or 0V with
the parport on the high side.

The parallel port is typically better at sinking current than sourcing
current. Some ports can only source 3mA but can sink 15mA. You may
need to invert the pins in Stepconf it the BoB is configured for
Active-low. (This is actually often a better arrangement, as you get a
nice solid 5V signal swing, even with a 3,3V parallel port)

Then you need to consider how the drives are wired. My drives have a
common +5V and then the signals connect to the low-side. This means
that my drives are _also_ active low, so if you had an active-low BoB
it would all cancel out and you need to un-invert the pins in
stepconf.

If you try to think in terms of the step and direction signals being
mediated by current flowing through optos (current-flow == ON) rather
than in terms of voltages then it will all make a lot more sense.

-- 
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto

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