Unable to configure external trigger input source in ULx VI for data acquisition from MCC DAQ board

[Sreedev D S]

Hi, I need to do voltage measurements using MCC DAQ data acquisition board. This board is accessible in Labview through ULx VIs and a number of examples are also there in Labview under the 'Hardware Input Output section'. But I need to acquire data in synchronous with an external TTL input. There is a 'ULx Trigger VI' to synchronize the data acquisition with external TTL input, but this VI has no 'source input' to select the trigger source. A similar VI in Labview named, 'DAQmx start trigger' VI in 'start digital edge' mode has a 'source input' to select the trigger source. This feature is lacking in the 'ULx Trigger VI' and so I am unable to access data synchronously with external TTL input. Please suggest a solution

[Fausto]

Hello @Sreedev D S.

Please provide additional information, i.e. LabVIEW version, MCC DAQ, InstaCal version, Windows OS version, ULx for NI LabVIEW version, screen captures, your VI example.

Regards,

Fausto

[Sreedev D S]

Hi, Sorry for the delay in reply. LABVIEW version: 2022 Q3 (32 bit), MCC DAQ: USB-1608HS, InstaCal version: 6.73, Windows OS version: Windows 10 pro 22H2. Screen shot of the VI attached.

The purpose of the VI is to acquire the data from one of the analog inputs of MCC USB-1608HS device in synchronous with an external TTL trigger input. But there is no option in the ULx Trigger VI to select the trigger source. If I select the composite start Ext TTL or Basic Digital Pattern instances of the ULx Trigger VI, Labview shows that those triggers are not supported by the specified device. Screen shot attached. Please suggest a solution.   

[Fausto]

Hello @Sreedev D S.

The USB-1608HS does support an external trigger for the analog input channels.

UL Help:  https://www.mccdaq.com/pdfs/manuals/Mcculw_WebHelp/ULStart.htm

 

Take a look at the 'ULx Acq&Graph Voltage-Int Clk-Dig Start.vi' example, found in the 'C:\Program Files\National Instruments\LabVIEW 2022\examples\ULx\Analog In\Measure Voltage.llb' file.  (Note: At the time of this post, ULx for NI LabVIEW is not supported in LabVIEW 2023.)

 

Regards,

Fausto

 

[Sreedev D S]

On 4/18/2023 at 8:02 PM, Fausto said:

Hi, Thanks for the reply. The issue I am facing is exactly this. With basic digital edge instance of the ULx Basic Trigger VI, I can specify the trigger edge. But where to specify the external trigger source? I have an external trigger signal and the data acquisition to be synchronized with this trigger. 

 

 

[Sreedev D S]

On 4/18/2023 at 8:02 PM, Fausto said:

Hello @Sreedev D S.

The USB-1608HS does support an external trigger for the analog input channels.

UL Help:  https://www.mccdaq.com/pdfs/manuals/Mcculw_WebHelp/ULStart.htm

 

Take a look at the 'ULx Acq&Graph Voltage-Int Clk-Dig Start.vi' example, found in the 'C:\Program Files\National Instruments\LabVIEW 2022\examples\ULx\Analog In\Measure Voltage.llb' file.  (Note: At the time of this post, ULx for NI LabVIEW is not supported in LabVIEW 2023.)

 

Regards,

Fausto

 

The MCC USB-1608HS has only one physical trigger input terminal. So when we select the basic digital edge instance of the ULx Basic Trigger VI as shown in the diagram, it automatically takes this physical trigger input terminal as the trigger source. So we don't have to specify the trigger source in the VI. Its working fine now. Thanks...

Edited April 27, 2023 by Sreedev D S