Digital Multimeters (DMMs) and Precision DC Sources

cancel
Showing results for 
Search instead for 
Did you mean: 

Trigger difference of niDMM_ConfigureMultiPoint vs. niDMM_ConfigureStartTrigger?

What is the difference of specifying the trigger source with niDMM_ConfigureStartTrigger and niDMM_ConfigureMultiPoint
0 Kudos
Message 1 of 5
(7,243 Views)
Hello,

The NI Digital Multimeters Help contains a detailed description of each niDMM function, including the trigger functions. I recommend referring to this document for detailed descriptions on the functions (from the Contents tab >> NI Digital Multimeters Help >> VI Reference).

As a tip, you will need to call the niDMM Configure Trigger function in addition to the functions you are looking at. This is the main function for configuring triggers. I recommend looking at the trigger example programs to see the different ways to set up triggers. If you have installed the NI-DMM drivers, the examples will be located in this d
irectory:

C:\Program Files\National Instruments\LabVIEW 7.0\examples\instr\NIDMM

I hope this helps!

Regards,

Sonya W.
Applications Engineer
National Instruments
0 Kudos
Message 2 of 5
(7,243 Views)
Yes, I have spent the first half of this week browsing help and looking in this manual or that manual, trying to understand the vague detail. Problem is the information is sparse and distributed here and there, and seems to be scoped more for Labview than CVI. I have exhausted my patients with looking at examples and browsing text. I would like someone to just tell me what I need to do and why. I have been using LabWindows CVI for the last 8 years and am not a novice, though I have only been using PXI instruments for a year now.
0 Kudos
Message 3 of 5
(7,243 Views)
Hello,

It seems this thread is addressing the same question as another thread which I just answered. Please follow this link to see my posted reply.

Regards,

Sonya W.
Applications Engineer
National Instruments
0 Kudos
Message 4 of 5
(7,243 Views)
Hello,

Looking at your first question and your comment, I realized you were looking for more specific information. In order to make this answer easier to read, I will break it into two sections: a) Explanation of the function niDMM_ConfigureStartTrigger and b) NI-DMM Programming Flow and Trigger configuration.

a) Explanation of the function niDMM_ConfigureStartTrigger
The niDMM_ConfigureStartTrigger function was included with the NI-DMM 1.6 driver. Once IVI released their complete specification for the DMM driver, the NI-DMM driver was upgraded to version 2.0, and this function was replaced by niDMM_ConfigureTrigger and niDMM_ConfigureTriggerSlope. I recommend that you use these functions in your new application, instead of the obsoleted one.
NI-DMM 2.0 (and later versions) still ship with the definition of the obsoleted functions, so your previous code will still compile. You can find the include file for the current and the obsoleted functions in the following folder: C:\VXIPNP\WinNT\include.
The obsoleted function niDMM_ConfigureStartTrigger allowed you to configure the source and the slope of the trigger. The function niDMM_ConfigureTrigger allows you to configure the trigger source and trigger delay. To change the slope of the trigger, use the function niDMM_ConfigureTriggerSlope.
Please make sure that you have installed on your computer the latest version of the NI-DMM driver, which has updated documentation and ships with a complete set of example programs for LabWindows/CVI.

b) NI-DMM Programming Flow and Trigger configuration.
The NI Digital Multimeters Help has information for both LabVIEW and text-based programmers. In fact, the function names are the same for LabVIEW and C. The basic programming flow of NI-DMM is explained under the section NI Digital Multimeters Help >> Programming >> NI DMM Programming Flow. Basically, what you need to do is Initalize (open a session), Configure (this involved configuring the measurement and triggers, and enabling or disabling features), Acquire and Close (close the session).
If you do not configure a trigger in your application, the driver will use the default value for the trigger, which is IMMEDIATE. If you are planning on configuring the triggers, please look at the entries Single Point Acquisition and Multi Point Acquisition under the section NI Digital Multimeters Help >> Programming >> Triggering.
From these sections you can see that the NI-DMM is capable of using two input triggers and generating one output trigger. If you program a single point acquisition, the DMM only uses one input trigger (I will refer to it as Trigger from here on), which is the one you configure with the functions niDMM_ConfigureTrigger and niDMM_ConfigureTriggerSlope mentioned above. Please refer to the shipping example program C:\Program Files\National Instruments\CVI70\samples\niDMM\Triggered\Single Point - Ext Trig .
When programming a multi-point acquisition you need to take into account two input triggers: Trigger and Sample Trigger. If you look at the multi-point acquisition flow in the image shown at NI Digital Multimeters Help >> Programming >> Triggering >> Multi Point Acquisition, you will see that the Sample Trigger is a nested loop of the Trigger loop. So if you wanted to acquire 100 points, you could set up the Trigger count to 10 and the Sample Trigger to 10, or you could set up the Trigger count to 1 and the Sample Trigger to 100, and so forth. You can configure the source and delay of the Trigger with the functions mentioned before and you can configure its counts using the function niDMM_ConfigureMultiPont. To configure the source and counts of the Sample Trigger, use the function niDMM_ConfigureMultiPoint, and use the function niDMM ConfigureSampleTriggerSlope to configure its slope. Please refer to the shipping example programs located in the folder C:\Program Files\National Instruments\CVI70\samples\niDMM\Triggered

Feel free to respond to this post if you have further questions.

Regards,

Sonya W.
Applications Engineer
National Instruments
0 Kudos
Message 5 of 5
(7,243 Views)