I am using a Conditional Retrieval Trigger but only recording data around a very narrow band relative to the set point. Any thoughts? Thanks

[JBomar]

Since I am pretty new to LabView, I have tried to build this with examples given and have things running my way except for this trigger problem. I would like to have my acquisition channel serve as my trigger channel and only log data after this point is reached and stop after the level goes back under the set point.

[JBomar]

Sorry.....wrong vi....try this one!

[JustinBritten]

Greetings,

A Knowledge Base article, on our website, does a very good job of explaining how to start and stop an acquisition using analog triggers. I have linked this article below.

How Can I Start and Stop an Analog Acquisition Using an Analog Trigger?
http://digital.ni.com/public.nsf/websearch/8737E90ABEE342BD862569EE0077F6D2?OpenDocument

Regards,
Justin Britten

Applications Engineer
National Instruments

[JBomar]

Justin,

Thanks for the reply. When I attempt to run this example VI I get error 10403 AI Trigg Config saying its an inapproproate operation for this device. I am running with a 6024E card on a CB-68LP board with "Test" configured through the configuration wizard and wired to ACH0. The VI I have been working with is attached below.

[JustinBritten]

I apologize, but I did not realize what hardware you were using previously. The 6024E card does not have analog triggers. It only supports digital triggering. Therefore, you will be unable to configure an analog start and stop trigger.

In order to configure a digital start and stop trigger, you may want to look at the following example program.

Continuously Acquiring Analog Signals Using a Digital Start and Stop Trigger in LabVIEW
http://venus.ni.com/stage/we/niepd_web_display.DISPLAY_EPD4?p_guid=B45EACE3ED3556A4E034080020E74861&p_node=DZ52308&p_submitted=N&p_rank=&p_answer=&p_source=Internal

The work-around since your board does not support analog triggering is to use conditional retrieval, which implements a circular buffer in c
omputer memory and checks each point as it is acquired to see if it matches the trigger conditions. When the trigger conditions are met LabVIEW reads the desired data from the buffer. Since the program you are pointing me to uses conditional retrieval, I will assume you already knew of this work-around. Basically you will no longer be performing a hardware trigger. Instead you will just be checking each input value to see if it falls in an acceptable range. Unfortunately, the VI you attached to your post is missing subVIs. I cannot open your attachment and run it with the broken subVIs. You will need to save your application as a library (llb) in order for me to view it.

Regards,
Justin

[JBomar]

I have taken a look at this and seem to require spoon feeding! With this digital triggering, do I connect my ACH0 (signal channel I wish to read) with PFI0? Also, the example does not seem to specify a trigger level; is that as simple as adding a control. One other question, on my CB-68, I measure 5.0 VDC between the DGND and PFI0...with no wire connections...is this correct?? Thanks

[JustinBritten]

Please refer to the I/O connections section of the example web page I sent you. On the page, before you download the VI, it reads the following ...

"Connect the analog signal to AI channel 1. The default input mode for the DAQ device will be used.

Connect both the start and stop trigger signal to PFI0. If you wish to use a different PFI line or use a separate PFI line for each trigger, you must change the trigger source on the Trigger Config VIs."

For your board you can use PFI 0-9 or RTSI 0-6 as digital start or stop trigger lines.

For more information on configuring your trigger, you may right-click on the AI Trigger Config VI and choose "Help".

Also, please refer to your board's User Manual for information
on the digital trigger lines. You will see in Table 4-2: I/O Connector Signal Descriptions that a low-to-high transition will indicate the initiation of pre and post trigger conversions.

6023E/6024E/6025E User Manual
http://digital.ni.com/manuals.nsf/websearch/0C88F40FFE7F28CD862569AE00574AC1?OpenDocument&node=1064_US

Regards,
Justin