A simple way to do this in LabVIEW is to use the Write to Digital Line VI within the Data Acquisition >> Digital I/O subpalette.
For most E Series devices, there is one port consisting of 8 digital lines. To output a 5 V TTL signal on digital line 0, use this VI and set the device number, digital channel to 0, line to 0, and line state to True. The device number can be found by looking within Measurement and Automation Explorer (MAX) and expanding devices and interfaces. The device number will show up by the device.
With regards to connections, you would want to connect to DIO0(pin 52) and DGND(pin 53). The pin-out of the device can be found in the user manual within chapter 4. I hope this helps.
PCI E Series User Manual
http://digital.ni.com/manuals.n
sf/webAdvsearch/06F1C9FB0D0BA5C286256C010057461B?OpenDocument&vid=niwc&node=132100_US
Regards,
Todd D.
NI Applications Engineer