Why Does My SCXI-1126 Module Read Incorrect Values in DAQmx, but not in Traditional NI-DAQ?

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Hardware: SCXI>>Modules>>SCXI-1126, SCXI>>Terminal Blocks>>SCXI-1327

Problem: I have an SCXI-1126 module with an SCXI-1327 connector block. When I read in values using Traditional NI-DAQ, everything works perfectly, but when I use DAQmx, all of the values I read are far outside the expected range.

Solution: The DAQmx driver removes most of the complexity of configuring your SCXI chassis and modules in Measurement & Automation Explorer (MAX), but some settings must be chosen manually. The SCXI-1327 terminal block contains a set of hardware jumper switches that control the high-voltage attenuator circuitry included on the terminal block. The attenuation circuitry, if activated, performs a precision 100-to-1 voltage attenuation on the input signal, and requires that the driver take this into account to perform an accurate measurement. To configure this in MAX:

Navigate to your 1126 module under My System->Devices & Interfaces->NI-DAQmx Devices.
Right click on the 1126 module and choose "Properties."
Make sure that the SCXI-1327 is selected as the Accessory.
Click "Configure.." and for each channel, choose the appropriate setting for the jumper (either 100 or 1).
- If all channels use the same jumper setting, select "All Channels" for the channel.

The Traditional NI-DAQ driver required different configuration settings and did not include a software verification of jumper settings. For more details on the user-selectable jumpers on the SCXI-1327, please refer to the SCXI-1327 Installation Guide under the "Configuring the High-Voltage Attenuator" section.

Related Links:
SCXI-1327 High-Voltage Attenuator Installation Guide

Attachments:

Report Date: 02/06/2006
Last Updated: 02/16/2006
Document ID: 3U59FBPZ

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