Chromatography Forum

Hi all,

I have set up an agilent 35900E analogue to digital interface to collect the signal from a chemiluminescence detector. It is working well, but now I need a way to turn off the detector for the first 3 minutes of the run so the detector doesn't overload with all the early eluting rubbish.

I have a relay card which I was planning to use to control the 24 V power supply for the chemiluminescence detector, and I can see the "timed events" menu for the ADC in chemstation.

What I don't know is:

- on the 25 pin plug for the digital I/O, which of the 9 pins are used for digital signals
- what type of signal is the output (I have got as far as "open collector" but I don't have a good grasp on what that means in practice). The software menu talks about "pin 9 high/pin 9 low", but what does that mean in practice, and how do I wire it up?

I spoke to Agilent and they said they didn't know about the pins, I should buy an external contacts board because it interfaces automatically then, but the ECB costs $400 AUD, and I bought my relay card for $30. If you have a digital I/O, you should really tell people what the signal is and on what pins I think?

If anyone has any advice/info on this you would be saving me a lot of time with a multimeter and oscilloscope!

Thanks very much

Jeremy

*bump*

Hi there,

I'm not entirely sure about the process and detector you're using but we have a method where we have to separate a lot of salt from our polymer sample on our agilent HPLC. We use a simple column switcher and divert the post column flow from our ELSD detector using the column switcher to waste so it doesnt go loopy with all the initial salt going through it and then we switch back to detector after 3 minutes. Not sure if this is applicable to you or remotely useful but it is a very simple way without having to footer about with software or turn off your detector!

lynz x

Sorry for this late reply to your post, but have you gone to Agilents document library online (Agilent.com) and downloaded the manuals? I have several of these a/d boxes and they are great, but to my recollection the digital i/o is not designed for capturing a digitized signal , that is, the chromatogram. It is strictly for control, reading BCD codes from autosamplers, etc.

go to page 32 of the following document:

http://www.chem.agilent.com/Library/use ... 016711.pdf