Chemstation/Agilent 1100 stupid problem

[bisnettrj2]

I have no idea what happened, but it did, and now I need to fix it. We use the Agilent Chemstation to control our 1100's. Normally, a run is started in Chemstation and signal acquisition is triggered by the injection. But now, my system begins a new run as soon as the last run is completed, but it takes the system about 2.8 minutes to inject the next sample, so I have some obvious retention time shifts. The stupid part is, I can't figure out how to fix this, and I don't even know how this started in the first place. Any ideas?

[Peter Apps]

I have had the equivalent problem with an Agilent 6890 GC running from Chemstation - as soon as a run was finished it would start another one, ready or not. It turned out not to be a sophisticated software problem - the start button on the GC was stuck !

Peter

[bisnettrj2]

If only it were that easy. 1100's don't have start buttons. It's got to be the software equivalent of your problem though, but I'll be damned if I can figure it out.

[AICMM]

Ping the guys at ACCTA one or two posts earlier in the data system section. They have their web page on their post and they look to know quite a bit about Agilent LC.

Best regards.

[bisnettrj2]

Thanks, will do.

[Dan]

In most cases, the start signal is a momentary contact closure that completes an electronic circuit, thus providing the start signal. The contact device can be either electronic or mechanical and, in either case, it can be controlled by software.

So, yes, it may be a software issue. I am not familiar enough with ChemStation to provide guidance on that. However, I have seen this problem caused by a physical error perhaps more often than by a software error.

My suggestion is to also look into a physical problem. The stuck button that Peter had was a physical problem that gave a constant contact closure rather than a momentary one.

I have seen two common physical problems that can give that constant start signal: (1) the wires (leads) of the start cable were inverted (i.e. they were contected to the wrong terminals) and (2) the leads of the start cable came into physical (electrical) contact with each other.

If you haven't recently disconected and re-connected the start cable, then number (1) is not your problem. Problem number (2) can occur with an old cable or by a cable that was recently moved.

Have you moved your instrument or cables lately? Did you just clean behind the instrument and cause the cable to be moved?

So, I recommend that you check the cable as well as look at the software.

Regards,
Dan

[promochrom]

If you are using a manual injector, you may check the remote cable from the injection valve. If your PC has other programs running at the same time, they may also cause the wrong start stop.
Regards,
PromoChrom
www.promochrom.com

[bisnettrj2]

I think I fixed it. I had the detector balance the baseline pre-injection, and for some reason this delayed the start of the data acquisition until the time of injection. Odd. Thanks for all the suggestions though, I appreciate it.

[mbicking]

It is typical to have the system do a baseline reset (i.e., "zero") before each injection. If you don't do this, the baseline could eventually drift enough to go off scale.

What version of software are you using? This is an unusual problem, and I suspect a setting in the method was accidently changed.

Are you using overlapping injection cycles, or any other injector functions?

Choose Method, Edit Entire Method and review your settings. If you aren't sure, write back. I'll try to reply sooner next time.

[moraespack]

Have you checked the remote control cable?

[mbicking]

This system communicates with the control computer through a network card on the detector. Other modules are connected to each other by network cables. There is no separate "start" cable. Since all connections are through the network cable, I believe this is a software problem, although there could be a problem with the firmware in the injector.

Try upgrading the firmware also.