Trying to create two AI channels of varying voltages but need same time domain

[josh100482]

I used the Multi-Function-Synch AI-AO.vi example to create two inputs of varying voltages while keeping the same time domain by modifying  the DAQmx create channel to an input.  Can someone explain how to do this?  I have left my code which seems correct to me as well as the NI example for one input and one output.

[Dennis_Knutson]

You are making this far too complicated and creating something that will generate an error. Start with one of the shipping examples for analog input only. After the DAQmx Create Channel, simply add another to the same task and define the second channel with different min and max.

Message Edited by Dennis Knutson on 10-24-2007 09:36 AM

[josh100482]

Will this allow both inputs be started at the same time if I do this? Or will they be out of synch?

[Dennis_Knutson]

The acquisition for both channels will start at the same time. Unless you have a simultaneous sampling DAQ board, there will be a slight delay between channels. Most of the NI DAQ boards use a single A/D and all of the channels are muxed to it.

[josh100482]

Thanks for the help and I'll incorporate that suggestion in my code.

[BrowningG]

Hello Josh100482,

Thanks for contacting National Instruments.

To add to the comments that Dennis left, if the channels you wish to measure are the same measurement type, you can specify a channel list using one create channel VI.  If you search in the DAQmx help file for the key words “physical channel syntax” the first topic will show how to specify a range of channels.  This could simplify your block diagram code if the parameters for the two channels you wish to measure were the same. 

Getting Started with NI-DAQmx and Learn 10 Functions in NI-DAQmx and Handle 80 Percent of Your Data Acquisition Applications are great starting points for programming with DAQmx. 

Have a great day!