Analog Triggers Don't Work Properly with SCC-AI0x moduleHardware: SCC>>Modules>>SCC-A10
Problem: After configuring the DAQ board to use the SC-2345 with an SCC-AI0x as its accessory, analog triggers don't work. How can I get analog triggers to work properly with my SCC module? Solution: NI-DAQ scales the analog input voltage for all configured SCC-AI0x modules based on the gain associated with the module, so when you do an analog input you will see the pre-gain voltage. When an analog trigger is set for a channel that is configured with an SCC-AI0x module, the trigger value is represented in terms of the post-gain voltage that the DAQ board sees, not the expected pre-gain voltage. This means that if you have an SCC-AI05, which has a gain of 10, and you want to set the analog trigger for .5 V (pre-gain), then you actually need to set the value for the trigger to be .5 V x 10 = 5 V. Workarounds: Traditional DAQ To calculate the value for the analog trigger, take the real world voltage that you would like to trigger off of and multiply it by the gain of the SCC module. Use this as the input for the function that is setting the analog trigger. DAQmx In National Instruments newest data acquisition driver, DAQmx, the analog triggers work correctly. You do not have to adjust the value of the analog trigger according to what gain you set. DAQmx does all this automatically. For more information about DAQmx and DAQmx software compatibility refer to the related links below. Related Links: What is DAQmx? Overview of Hardware and Software Support in NI-DAQmx Attachments:
Report Date: 01/28/2003 Last Updated: 03/14/2004 Document ID: 2TR8KM2G |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
