🚀 go-pugleaf

In article <845933481.19107.0@intra.demon.co.uk>, Paul
<paul@intra.demon.co.uk> writes

>I am looking to switch on/off various pieces of equipment by writing
>software routines to interface between the com port and the equipment.
>
>I have noticed when I open the com port the voltage across certain pins
>increases from zero volts to 20 volts. Is there any way of utilising
>this voltage increase to 'control' equipment.

Yes is you only want a few bits.


>Initially I am just looking to switch on/off a 6V cassette recorder but
>eventually I would like switch on/off some 3 phase (330V) stepper
>motors.

Let's make certain that this is right.

  Do you mean

    3 phase motor

  or

    3 pole stepper motor ?


330 Volts seems a lot for a stepper !

Once we know exactly what you want to control, we can comment on the
interface needed.


>I have seen the 64 channel i/o controllers as advertised by Maplins at
>�80 but I have no real idea how they work. What are 64 channels needed
>for ?

Err, something that needs that many of course !  :)


>  It appears that other hardware is also required, like relay
>boards.

Relays may not be fast enough for steppers.  You'd probably need GTOs or
big FETs for steppers or triacs for a 3-ph motor.


> The relay boards at �120  appear to only operate at relatively
>low power consumption (120V 2amp).

??  Run that by us again !


> Surely there must be some cheaper way
>of getting a PC to switch on/off a cassette recorder than �200.

Of course.  How's your soldering ?  Do you have an RS account ?


Cheers, J/.
-- 
John Beardmore