Can External Referencing Be Done On a Per-Channel Basis?Primary Software: Driver Software>>NI-DAQPrimary Software Version: 7.2 Primary Software Fixed Version: N/A Secondary Software: Utility Software>>Measurement & Automation Explorer
Problem: I want to externally reference one analog output channel while internally referencing another analog output from the same device. Can this be accomplished? Solution: Generally, referencing data is specified on a per-device basis in the Measurement and Automation Explorer (MAX). AO_Configure, a Traditional NI-DAQ function call to the DAQ API, allows this referencing on a per-channel basis. Use DAQ API calls throughout the code. The AO_Write and AO_VWrite runs according to the configuration set with the AO_Configure. When you use EasyIO calls such as AOUpdateChannel and AOGenerateWaveforms, per-channel referencing is not observed. These EasyIO calls are not straight DAQ API calls. At some point in the source code, a configuration is enabled that overwrites whatever data is established with the AO_Configure call. This configuration is based on the settings in MAX that are on a per-device basis. The attached text file demonstrates this functionality. Channel 1 is configured for bipolar internal referencing of 10 V. Channel 2 is configured for bipolar external referencing at 5 V. When you run this program with a 12-bit device (such as the NI 6711 or 6713), Channel 2 sends a signal with 2.4 mV resolution while Channel 1 maintains the expected 4.8 mV resolution. Related Links: Attachments:
Report Date: 01/23/2004 Last Updated: 06/29/2004 Document ID: 35MDD3WX |
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