Re: help for a newbie

Wohoo! I finally got it!I just backed up and did exactly what Caudlet
says below and I found the problem. No Signal. I was trying to use a
ISA Parallel port card that was stuck in the computer. I wasn't
getting anyting from it. I took out that card and tried the other
port built into the board and it worked. I built my own little logic
probe just like you said. I dropped by radio shack on the way home
and bought the led and a resistor and mounted them on a little board
with a terminal block. It worked perfectly.
Thanks again for the help. I did notice that the motor turned much
slower than what I thought it would, and I could make it start
missing steps with my hand. These are 475 iz-in steppers. That makes
me curious. I do believe I have a lot of tuning to do.
Thanks again for all the help!
Kelly Sprayberry

>
> Okay, here's some things to try:
>
> DO THESE TESTS WITH THE GECKO's DISCONNECTED FROM THE COMPUTER.
>
> Build yourself a poor man's logic probe. Use an LED with a 470 ohm
> resistor (yellow-violet-brn) soldered to either leg of the LED.

Test

> the "probe" by connecting it with the Anode to the +5 supply source
> and the Cathode to Ground (small insulated clip leads can help
> here) . If it lights you have connected everything right. Failure

to

> light might indicate the LED is backwards. If you get real
> industrious you can use two seperate leds hooked up with resistors.
> Then you can monitor both step and direction signals at the same

time.

>
> Now, leave the Anode(s) connected to to +5 and the cathode(s) to

one

> of the signal lines (step and/or direction) on the appropriate pin

(s)

> of the parallel port. You might want to use a breakout card (if

you

> have one) or an old DB25 connector to make the hookup easier. Fire
> up your control program on the computer and do some slow jogs on

the

> axis where you have the LED. With the DIRECTION pin you should see
> the LED go off and on in a steady state as you change the direction
> of the jog. The glow should be bright and steady when it comes

on.

> If no change in the lamp, make sure your software is setup for the
> correct PC port (normally hex378 - LPT1)and you have correctly
> defined the pins for that output signal. If the LED does not glow

as

> brightly as when it was connected directly across the +5 then

suspect

> that your parallel port pin definitions between step and direction
> have been switched (normally causes the motor to rotate

erratically)

> or that your parallel port is not able to "sink" enough current to
> properly drive the Optoisolators in the Gecko's.
>
> The STEP pins will glow less bright because they are being pulsed.
> If they do not change state when you jog then you are not getting
> signal to that pin.
>
> To test the input of the Gecko's: Apply motor power with a motor
> connected. Connect the seperate + 5 and ground (from the +5 source)
> to the correct INPUT pins. Disconnect the signal (step and
> direction). With a clip lead on the direction pin of the Gecko
> momentarily ground the pin to the ground from the +5 source THIS IS
> NOT THE GROUND FOR THE MOTOR POWER SUPPLY. The motor

should "twitch"

> each time you ground the step pin. The direction may not be
> predictable but it proves the GECKO is probably fine and will run

if

> given the correct level of signals.
>
> All of this becomes easier to do if you have test equipment but
> simple voltmeters can be hard to read correctly. A scope is handy
> but most guys don't have that type of equipment laying around.
>
> Since the optoisolator is just an LED and a light sensitive
> transistor the little rig I describe allows you to "see" the signal
> that normally happens inside the opto.
>
> Let us know if you still are having problems.