PLEASE HELP!!what is the function of this keithley output source VI?

[SG_SP_OLED]

i would like to know what does "trigger delay","sour delay","NPLC","arm count" do in this example.Please help!! thanks!!=D!!

[BiomedEE]

I don't have your Keithley device handy to try out the code but I have written a lot of GPIB VI's for these kinds of devices. When a company like Keithley gives you these types of GPIB drivers, one in general copies out only the useful functions to the particular test or capability that one wants. The manufacturer will give you an example like this that sets all kinds of parameters, probably having nothing to do with the usually much more minimal needs in the lab or test at hand. That fact that you don't know what they do tells me you probobly don't need them. If you did you usually just look them up in the pdf file or example VI as needs dictate. To get started copy the parts that seem like they do what you want into a new Vi. Run your test or experiment through LabView to see if it did the job. Add extras if it did not set the device up the way you want.

Several months ago a customer of mine bought a Taiwan branded meter that had a snipet of GPIB LabView code, it looked similar to yours. I never used any of it. I just went straight to the list of commands in the pdf file and wrote my own into a simple Vi to incorporate in testing. Sometimes they are trying to give you examples of stuff that may never be used the whole time you use the meter.

If you really want to know all the capabilities of the device you just have to sit on a bench running the examples. Sometimes that can be helpful in the long run just to know all the things the device can do.

[tbob]

I didn't open your example (I'm not at my work computer), but here is an explanation of the terms:

Trigger delay is the amount of time between a DMM being given a command to take a reading, and the actual reading being taken.  Lets say you want to read the voltage on line A exactly one second after the voltage on line B goes above 2V.  You set the DMM for external trigger with line B connected to the external trigger input on the DMM.  THen set Trigger Delay for 1 second.  Then send the command to read the DMM (Read?).  The DMM will become armed (waiting for trigger).  When line B goes above 2V, the DMM will wait one more second, then read line A.  If you don't want to wait to take a reading, set the trigger to immediate.

Sour stands for source.  I've never heard of source delay.

NPLC is the Number of Power Line Cycles.  In the U.S., we use 60Hz power (50Hz in Europe), so one power line cycle is 1/60 seconds.  When setting NPLC, the DMM will take continuous readings for that length of time, then take an average of all the readings and return this value.  Setting NPLC to 10 will make the DMM take readings ofr 10/60, or 1/6 seconds, and return the average of all readings.  How many readings can be taken during that time interval depends on the DMM, the range setting, and the resolution setting.

Not sure about "arm count", but "arm" means that the DMM has been given a command to read but has not yet received the trigger to take the reading.

Reading a DMM through GPIB involves a series of events:  Arming (GPIB command to read or measure), triggering (immediate or delayed, internal or external), measuring (one measurement or several for averaging), then returning the measurement.

Message Edited by tbob on 05-29-2006 11:54 AM

[SG_SP_OLED]

woah thanks alot!at least i know most of its functions now=D big ThanKs to YoU!=>