How to control a TTL device using LabVIEW?

[ddeng]

I have a device which requires TTL (+5V) to turn it on/off. How can I control it using LabVIEW? I guess I should install a PCI board in my computer to connect to that device, but how to control it in my LabVIEW code?

[Sean_C.]

Hello,

You could install any of National Instruments' DIO boards to control a TTL device. Then using the NI-DAQ VIs that come with the NI-DAQ driver, you could control the device.
See one of the Digital Output examples in the Example Finder (Help >> Find Examples) for help on setting up this system.

I hope this helps,
Sean C.

[Steve Parus]

You could use the parallel port and LV's OutPort.vi. The parallel
port can really only output a few milliamps though. More than that
and its voltage drops from the nominal 4 V. A low gate threshold
mosfet can be used to drive (sink) more current, such as the
RFP30N06LE, available from DigiKey for $1. These turn on with 2 V.

Or use a photo MOS or Opto MOS isolator. These are basically
encapsulated led's lit by the parallel port current which are
optically coupled to an fet. So they act like an isolated solid state
variable resistor. They are available with a few mA drive current.
No power supply needed.

Or use a power mosfet driver. These take TTL logic level signals at
very low drive current and either source or sink Amps of current.
Look up
IXYS at DigiKey.

Steve