Reading a trigger event through Serial or USB

[Y3G]

Hi,

I am trying to read out from USB or Serial port (today its USB-Serial converters) a TTL level event that will cause a SubVi to run. The TTL event will be supplies by a Signal Generator's BNC output.

On a Serial Port I could listen to Pin2, but haven't figured out yet how exactly. The TTL level

I haven't figured out if to use a USB or the Serial port, since nowerdays the PC are not equipped with a serial port.

Any Ideas are welcomed.

Thanks

Y3G

[johnsold]

Y3G,

You could poll one of the handshaking lines using property nodes.  Some USB to RS-232 adapters are better at dealing with handshaking without any data at the port than others.

You are aware, are you not, that RS-232 lines are not equivalent to TTL levels?  Connecting TTL signal to an RS-232 receiver may not work and could destroy one or both devices!

An inexpensive DAQ device might be a better choice than trying to make some other device do something which it was not designed to do. The small amount of money you might save may be exceeded by the time, effort, and damaged equipment you spend trying to get it working the way you have proposed.

Lynn

[Y3G]

Thanks Lynn,

Any specific DAQ device you could suggest for that porpuse? What's about the latency time one have to conclude through such a device?

Rgds

Y3G 

[Cole_R]

Hi Y3G,

You may want take a look at some USB DAQ devices.  They are easy to use and setup.  Might want to have a look!

http://www.ni.com/data-acquisition/multifunction/

Cheers,

[MoReese]

You can also look at Measurement Computing devices.  They have many USB I/O modules to choose from with LV VIs.

[johnsold]

If you want specific recommendations, you will need to give us hard data about the magnitudes and frequencies or pulse widths of your signals.  How much latency between the trigger pulse and the start of the subVI is allowable?

Lynn