Connectivity

According to the manual, the GPI outputs are active low; the illustration shows a load of an LED and resistor being pulled to ground.

The issue is this: I need to combine several tally outputs to indicate when a particular source is switched to either of two destinations. How the GPI output circuit is designed will determine how easily I can make this happen:

- If the GPI outputs are either open-collector (through a driver like a ULN2803, for instance) or relay contacts, I can merely connect the outputs together and achieve a wired-or result;

- If the GPI outputs are bipolar -- that is, they try to assert a logic high when inactive -- then I need to use switching diodes to produce the 'or' function.

Can you shed some light on what the output circuit looks like?

Thanks!

-- Jeff

Hi Jeff,

The ouputs on the NK-GPI are open collector, through a quad opto-coupler. There are no current limiting resistors, and the maximum collector current that the optocoupler can handle is 50mA per channel.

If you need further details, please let us know.

Regards,

-Ralph

#NK

Ahhh... sounds like you're using something like the TLP504A-2's that I build into most of my interfaces. That's exactly what I was hoping to hear. Thanks for the information!

-- Jeff

#NK