how to check the speed of agilent 34907a

[siva0182]

Hope i am not duplicating my previous post.But i am not able to locate my previous post so i assume that it has not been posted yet.

The clarification i want to make is as follws:

I am reading data from a keithley sourcemeter through a GPIB cable and then process it and then write a digital output value to agilent 34907a multifunction module card and write the time ,GPIB data and the digital value into an excel sheet.

i want the whole cycle to run as fast as possible.

So I created a sequence of two frames(ref attached picture ) first frame reads GPIB data and second frame processes the data and writes output to agilent digital output module.

i have put this sequence inside a continous while loop.

There is no delay inserted anywhere.

The excel sheet shows a time difference about 60 msec +/2 sec between consecutive time readings.which means the output module has recieved a data every 60 msec .but i am not sure if it is able to execute the  commands it recieves or some commands ignored.

a.I can see alternate values being written in the display with no error. so does this mean all the write commands are executed?

b.does the nest while loop start only after the end of the write process?

c.Currenly i am using a rs232 cable as interface at 9600 baud rate can increasing this bring down the time from 60 msec?

your help would be highly appreciated 

regards

Siva 

[siva0182]

any help or insight int o this problem would be appreciated

thanks

Siva 

[LV_Pro]

Your previous posting of this question was in the LabWINDOWS forum. You can find any of your previous postings by clicking on your forum "name", it will show you every posting you have made.

I am unable to view your image attachment, it is too low resolution. You can attach source code, if it isn't too large, to your postings, just make sure to identify which version of LabVIEW was used.

 You say that your excel spreadsheet shows a time difference of 60 msec +/2 sec  what does +/2 mean? Plus or minus 2 seconds would be big if the expected/desired loop rate is 60 mS.  I don't know whether any commands are being ignored, you would probably get an error if it wasn't able to execute a command in time. If you are looping at 60 mS you won't be able to visually if a command is dropped, but depending on what it is (like output a level) it probably can handle it, that is only 17 S/sec roughly. The 34907a doesn't have a BW rating for the analog output that I could find, looks like it is expected to be used in more or less a static voltage source mode, but it does spec a 1 mS settling time, which should fall within your limits, assuming you are doing the next in measurement too soon.

Look at your previous post for other comments by another author.

[LV_Pro]

I see that you found your other posting.

LabVIEW, being a data flow language, executes "commands" in the order that they are "wired" or in the case of a sequence structure, one frame at a time. That having been said, there are some sub-vi calls that will wait until the underlying code has executed before continuing, others (usually dealling with hardware) that just send the message out to the device, then move on, since they aren't expecting/waiting for a response from the device. I haven't used the hardware you are using, the Agilent/HP stuff, in about 5 years so I don't recall if it is a "set and forget" or "send a message, wait for an acknowledgement" protocol.  Can you attach the code? Specify which version, I'm using 8.6 here, have 2009 on my laptop at my other office.

[siva0182]

Thanks for the replies.

I am not using analog output.i am using only digital output.

Though i am using only one bit ..i still need to send the whole byte of date with the last bit alone changed.

I have attached the stripped version of the actual pgm. 

regards

Siva

[siva0182]

i forgot to tell you the version ..the version of the pgm i have posted is version 8.

[Dennis_Knutson]

I don't know why you would post that. It's got too many broken wires and the wires it does have are going in every direction. In other words, it's a complete mess.

I also don't get your question. What exactly makes you think the instrument is not working?