Signal Conditioning for input of 6-7V on/off signals into Digital Inputs of NI-6040E?

[EngrTanveer]

I have to read on/off signals from 6-7 Volt limit switches, I must use a NI-6040 (PCI-MIO-16E4) board's 8 DIO lines for this. I need to use optocouples and I need some sort of circuit diagram that converts 8 V signals to TTL signals that the 6040 board can accept. I tried using a circuit (attached wmf file) but it doesnt work. Any help would be greartly appreciated.

[EngrTanveer]

I have solved the matter myself. Simply adding a 1k resistor between the DIO0 and DGND pin gets the job done.

[RIO-Todd]

Thanks for updating us with the answer to your post.

Another possible solution would be to use a Schmitt Trigger to convert the signal to a TTL level. The linked document below discusses using a Schmitt Trigger to get a signal to within the TTL specifications.

How Can I Convert My Signal to a TTL Compatible Signal?
http://digital.ni.com/public.nsf/websearch/771D82A44F27A0AF86256DD0007FB9A1?OpenDocument

Regards,

Todd D.
NI Applications Engineer