advanced scan vi agilent used for continous measurement

[Dennis_Knutson]

I'm not sure which queries have not been answered already so I will start with the basics.

If you are not familiar with the manual, you should first read that to get an idea of how the instrument works and what a scan does. A scan can be performed on multiple channels or the same channel. The time between measurements in a single scan is a function of the instrument and something that can be changed.

If you want to do multiple scans, then the code could be in a while loop. I believe one of the examples shows this. Essentially, you command the instrument to take one scan, you retrieve the data, and then initiate another scan. I don't have the manual or driver available right now but I think there was an instrument mode where you could command it to perform multiple scans. There is a limitation on how many scans it can perform and how many measurements it can store internally. Again, you really, really need to get familiar with the instrument manual to undertand the different modes.

The baud rate only affects how fast you can transfer data to and from the instrument.

[RTSLVU]

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siva0182 wrote:

But is a while loop required to read data continously .If so what vi's need to be inside while loop the trigger and read or the read vi alone.

Moreover how is the timeinterval between two readings controlled. I see there is an option in trigger vi.

BUt is an external wait timer required in the loop?

can anyone post an example of the continous advanced scan vi  they have used .Thanks

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Yes, you will need to use some sort of loop because the scan vi makes one scan of the configured channels, converts, and transfers the data then exits.

The agilent will not just continusally spit out data like the monitor function on the front pannel.

If your program needs to be doing other things at the same time I would suggest making a sub vi that runs in the background continusally scans the agilent and writes the reading to a global. Then you main program can simply read the global since it should contain the most recent reading.

Here is the scan vi I use, it is just a slightly modified version of the agilent supplied vi.

Remember thei vi only triggers a scan the channel(s) you want to read must be fully configured before running this.

[siva0182]

1.so what was the maximum no of readings per second were you able to read using the above program?

2.Also what is the advantage of this advanced vi over Ez temp vi since even that can be used in a loop to read continous data.

3.Is 30 channels per sec reading possible using rs232 and advanced/Ez   vi's.

4. what about delay timers that were required before configure and scan as mentioned in the intial posts in this thread.Your pgm does not seem to have those?

[RTSLVU]

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siva0182 wrote:

1.so what was the maximum no of readings per second were you able to read using the above program?

2.Also what is the advantage of this advanced vi over Ez temp vi since even that can be used in a loop to read continous data.

3.Is 30 channels per sec reading possible using rs232 and advanced/Ez   vi's.

4. what about delay timers that were required before configure and scan as mentioned in the intial posts in this thread.Your pgm does not seem to have those?

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1) It depends on how the channels are configured, the type of measurment and if you are doing any integration.

2) The adcanced vi's are a little faster because the channels are configured once and then just scanned as needed. The EZ vi's configure a scan, then scan it everytime.

3) Again it depends. If you are only scanning thermocouples then 30 chan/sec could be obtained as long as your RS232 is running at a high enough baud rate to transfer the 30 channels of data in under a second.

4) Configuration delays? I don't recall ever having to use any delays in configuring. But it does not matter anyway because using the advanced vi's you only need to configure the channels once at the start of your program. After that you use the scan vi to take a reading.

[siva0182]

Thanks for the clarifications.I will try out your suggestions...

But the last (point no 4)  one was about delays to be added to make the advanced scan work properly even for a single scan as discussed in this thread.

 http://forums.ni.com/ni/board/message?board.id=170&message.id=249889&query.id=726386#M249889

[siva0182]

adding to the above post is there an advanced vi option for 34907A module card (which  can send analog output signals).

[Dennis_Knutson]

You've got the Analog Output function. This is on the Action/Status palette. To control the digital outputs on the same module, use the Digital Output function on the same palette.

[RTSLVU]

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siva0182 wrote:

Thanks for the clarifications will try out your suggestions...

But the last (point no 4)  one was about delays to be added to make the advanced scan work properly even for a single scan as discussed in this thread.

 http://forums.ni.com/ni/board/message?board.id=170&message.id=249889&query.id=726386#M249889

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Hmm, I just read that thread and have to say again I have not ran into that issue. I currently have a project that uses two fully loaded (140 total channels) Agilents connected at 57600 baud via rs-232 using USB/rs-232 adaptors. I configure both loggers in one vi using LV 8.6 without needing any delays inserted.

If you are getting comm overruns or other errors when configuring you might need to add them.

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siva0182 wrote:

adding to the above post is there an advanced vi option for 34907A module card (which  can send analog output signals).

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I see Dennis answer this already I believe teh 34903A module has two 0-10V analog outputs

Message Edited by RTSLVU on 08-07-2009 07:28 AM

Message Edited by RTSLVU on 08-07-2009 07:30 AM

Message Edited by RTSLVU on 08-07-2009 07:31 AM

[siva0182]

I still seem to be having problems with advanced scan vi......

1.The pgm for single channel read with delays also seem to be working only in "highlight execution mode" in normal mode even though i have configured temperature reading seems to be in Volts. but in highlight execution mode it works correctly and the correct value in deg C is shown.

2.Second I tried to loop the read vi inside a while loop and in highlight execution mode the value of the reading does not change with every run in the loop ...eventhought tyhe temperature was changing physically.

I dont understand if the loop contains the necessary vi's ..

3.I dont understand the conf trigger vi.(difference between time scan interval and interval value?)

4.I dont understand  the max trigger count and source inputs of conf trigger vi.

I am posting the vi wgere i tried to put in a while loop.Please check what 's the error(s) ?

Alternatively if there is a trusted code for continous temperature measurment using advanced scan vi please do post the same.

[Alain_S]

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Dennis Knutson wrote:

The time between measurements in a single scan is a function of the instrument and something that can be changed.

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Maybe you overlooked this information from Dennis.

Whatever configuration vi, comm port ... ... you are using if the measurement setup is wrong you will never get 60S/s.

If I'm not mistaken there's something like PLC (Power Line Cycles) in that instrument.

That means that it takes multiple readings to filter out some noise from power lines. If you have PLC set to 10 for example, you can get only 6S/s (with a 60Hz power line system) whatever software and comm port you are using.

Other time settings that can prevent to reach 60S/s are "Scan interval" time between two scans and "Channel delay" time between two channels in one scan. I remember only these two for now but there can be more!

You see there are a lot of parameters that can prevent you to reach 60S/s