Re: L297 / L298 Help Required Pls!

Sorry for not replying back sooner I have been away for a couple of
days....

Ok Ill try and explain more clearly ....

The stepper controller is using 12v at the Step / Dir pins on the
euro connector.
The Step/Dir on the L297 is at 5v so this is OK.

The voltage is always High (12V) on the Step/Dir of the euro
connector on the stepper card.
What I think I need to is sink the 12v to ground producing a LOW.

I have seen some circuits on the web that look like the below....

12v
Step (from Eurocard)

|
|
B | /C
D0 --------R1K------|/ TR1
|\
| \E
|
|
R
|
|
------------------------ Gnd


Now from what I understand .. When D0 is High (5V) it basically
grounds the Collector input (Step 12V) thus sending it Low.
Now what I want is the reverse to this i.e. when D0 is low it the
Step (12V) goes Low and when D0 is High (5V) the Step (12V) is High
i.e. at 12V.
Ideally an opto-coupler would be sitting between the Parallel port
and transistor.

Hope this explains a little more.

TIA
Steve

--- In CAD_CAM_EDM_DRO@yahoogroups.com, RichD <cmsteam@s...> wrote:
> Steve,
> You have to fill in more detail.
> Where exactly are you checking this 0-12V?
> At the output of the L298? or the input of the L297?
> The L297's are 5V logic devices only.
> The input to the L298's are too, but the outputs (motor coil drives)
> are whatever the motor supply voltage is. Is this the 12V you
mention?
> The outputs (motor coil drives) are phase drive and will seem weird
> to see a correspondence to the step input.
> Otherwise, I see no problem so far.
> What IS the problem you have? Does the motor not step with step
input pulses?
> RichD
>
>
> paragon032003 wrote:
> >
> > John / Rich
> >
> > Thanks for your reply's!
> >
> > This is what I have found since the original post...
> >
> > The stepper driver cards are running at 12V for hi.
> > On the logic board there are three ILD74's (Dual opto transistors)
> > these are accepting between 0-3.5V Lo/Hi respectively its set
high by
> > default then pulses down to low (step takes place) then back to
hi on
> > the output side a single pin reads 12V and pulsates down to 0
this is
> > connected to the stepper drives the DIR side is the same but
toggle
> > between high and low (high = Clockwise).
> >
> > Does this make any sense?
> >
> > I presume that when the logic side goes low it sinks the 12V side
to
> > ground via a resister this then produces a low.
> >
> > Does this sound likely?
> >
> > TIA
> > Steve.
> >