Re: Lost steps

What may be overlooked here is the intermittent nature of the problem
originally reported.

If you don't want to have a system plagued with noise problems, do
the ground wiring right from the beginning. Right means use the
concept of a "holy point ground". This means ALL ground wires are
returned to a single point; power supply ground, motor drive ground,
parallel port ground, in short if it has a ground wire, take it to
that point! If shields are used, take them there too.

Resist the temptation to "daisy chain" ground wires. It can be
tempting to run a 3" wire from one device to an adjacent one where
otherwise it would be a 3 foot wire run back to the "holy point" You
won't be doing yourself a favor by taking the shortcut.

The whole point is to keep a level playing field. Voltages are always
relative. That is why it takes 2 leads to measure them. For most of
us that means "relative to ground". But what happens if one device's
ground has +/- 2 volts of high-frequency noise on it relative to
another device's ground? It will be added with the signal voltage and
no bypass cap will help there.

A single point ground "levels the field" so every device has the same
point of reference. It really saves a lot of grief.

Mariss

> OK, what Peter is talking about here is putting small value

capacitors

> across the signal inputs (one from signal ground to step in, and one
> from signal ground to direction in) right at the stepper driver
> terminals.
> I would recommend 100 pF (Pico Farads) as a start. This will remove
> extremely short duration noise pulses that are picked up by the

wiring.

>
> Jon