Re: [CAD_CAM_EDM_DRO] port problem

Terry Ackland wrote:

> Guys,
> I have finally got around to connection up the recommended relay
> (CX240D5) to my parallel port and a spindle but I am not having any
> luck.
> I can turn the 5 volts on and off using M-codes but there does not
> seem to be enough current to operate the relay.

Is this a solid state relay? How do you have this wired? Is the + of
the SSR connected to
the port pin, and the - connected to ground? This requires the port to
SOURCE about
3-5 mA to the relay, and is not likely to work. It might work if you
hook a resistor of
about 150 ohms to the port pin, and the other end to a source of +5 V.

The other way is to connect the - pin of the relay to the port pin, and
the + terminal
of the relay to a +5 V source. this requires you to program the port
bit LOW to turn
the relay on. Generally, the ports have more current SINK capability
than source.

Jon