The 7334 controller only outputs 2V, not 5V, when connected to parker z-drive

[baxter98]

Output voltage of card went from 5 volts down to 2 volts once it was connected to the driver of the motor- without 5 volt pulses, we cant drive the motor. Why is the hardware not able to send the direct signal? do we need an amplifier?

[Brent_R]

The inputs to the Parker drive are most likely optically isolated and require more current than the card's output can source. This is very easy to remedy. The outputs on the 7344 are configured as open-collector with 3.3k pullup resistors. This means that the card can only source 1 mA or so, however it can sink over 60 mA. Instead of connecting the 7344 output to the + terminal on the drive, connect it to the - terminal and connect the drive's + terminal to +5V. This way, the card is sinking current from the drive. Alternately, you could leave the system in it's existing configuration and add an external pullup resistor (500 ohms or so should work) between the drive's + terminal and +5V.

You can find a little more detail in the link below.

http://digita
l.ni.com/public.nsf/websearch/AEEE50B345A16951862566A20051076D?OpenDocument

Regards,

Brent R.
Applications Engineer
National Instruments

[baxter98]

Thanks Brent. That was the solution, we actually figured it out yesterday afternoon. Thats why you always check the diagram. Again, thanks.
Rudy