Triggering

[MartinBioeng]

I am running an old Applied Biosystems Capillary electrophoresis analytical instrument and using Labview for data acquisition. I have written a simple program using the DAQ assistant. I would also like the program to record the data collection as soon as the analysis starts running (ie to be triggered). The instrument has a trigger output which consist of 2 relays. One is for a strip chart recorder and both are for starting and stopping an integrator. The integrator relay is tripped by a brief pulse "on and off" where as the strip chart recorder  is turned on as long as the electrical contact is closed.  I have tried both these connections to trigger the data acquisition without any success. I connected the instrument "relay" terminals to "PFI0" terminal of a BNC2110 unit using a BNC connector. In the DAQ assistant software I went to "Task Triggering" and clicked on "Digital Edge". None of the other two "Analog Level" and Analog Window" were available. I also clicked on "PFI0" and "Rising Edge".  I started the anlaysis on the instrument but this did not trigger the data acquisition.When run manually the data acquisition works fine ie when the instrument is turned on and then the data acquisition started manually by clicking on "Run".
Any suggestions would be gratefully recieved.

thanks,

Martin

[LV_Pro]

I know this is pretty basic, but how are the relays wired (contact side)? Are they pulled up to 5v (through a resistor)? In many cases they would be triggering their "normal" devices by just acting as a switch, but for most DAQ boards you need to either pull the trigger pin either high or low.

P.M.

[johnsold]

Putnam,

I think you didn't have enough coffee this morning. The line to the DAQ trigger should be connected to the junction of the resistor and the relay contact.

I suspect that you are right about why it is not working.

Lynn

[LV_Pro]

Oops, spent too much time screwing around in Visio drawing it, not enough time looking at what I had drawn! Had a lot of coffee, mostly decafe though (got a visit with the Cardio guy tomorrow wanted to get the H.R. down to "normal"). Good catch.

P.M.