Chromatography Forum

I'm fishing for any ideas.

I'd like to simulate a chart recorder on a computer. I have a process analyzer that tends to take a long time to stabilize (hours), and it'd be helpful to be able to look at the output over time to see if it's still drifting or not.

A good ol' fashioned chart recorder would do the job, but buying one, keeping it stocked with paper and ink, etc, seems like over-kill. (And a hard sell to my boss.) Especially since I don't need a paper record, I just want to look at the signal over time.

Question the First: Is there software out there that will basically be a chart recorder? No, wait, I know there is--the real question is, is there cheap software out there that will do this?

Googling I found the DataQ starter system which, at $50, is definitely the right price. However, the hardware apparently cannot accurately measure a 0-200mV output, which is what the instrument has.

Question the Second: does is seem feasible to whip up a little amplifier that boost the output by 50x to 0-10 V and therefore use the DataQ?

Also, we actually have a Varian Star 800 Module Interface that was bought for a similar application, then never used (before I got here). Looking at the manual for that I think it will work on the hardware side, but I'm not sure about the software side. I don't want software that's expecting a run to start and stop and have peaks. I just need to see a chart-recorderesque output. Based on my limited experience with Varian Star Chromatography Workstation (v 6.4) running a Micro-GC, I don't think it will do what I want. (Indeed, I don't think I want to use it any more than I must.)

Question the Third: Will Varian Star Chromatography Workstation do what I'd like it to do? Any tips on how to make it do it?

Any other ideas, thoughts, criticisms, etc?

Thanks.

As you are looking for a one channel datalogger, you might find some cheap handheld/benchtop multimeters have the capacity for realtime logging onto a PC through a serial port.

The 0-200mV might also be covered by some temperature logging PC modules, and you could also look at a cheap signal conditioning module to modify the signal from your device.

I suspect the best sources of information could be some of the electronics hobby sites/communities on the WWW, and their various datalogging suggestions.

Good luck, and please keep having fun.

Bruce Hamilton

Try the LabJack device. It connects to the computer through the USB port and has some sample software with it that will simulate a chart recorder.

It has 8 A/D channels with a programmable gain amplifier that will get you 12 bits of A/D at +/- 1.0V. That should give you enough resolution to do a simple chart.

The device cost around $100 and comes with LabView software.

Flybeaux