04-17-2012 09:54 AM
I'm trying to confgigure the PXI 5922 for DIFFERENTIAL signal Acquisition. I have found the property, "Terminal Configuration" during search. While using this property, I'm not sure how the channel needs to assigned. For instance, I changed the property , modifying the niScope EX Windowing.vi example, and this is giving me channel error.
Appreciate a quick reply
05-07-2012 07:04 AM
The 5922 doesn't support a differential input for a single channel. However the card can be setup to output the (calculated) difference between both channels.
See NI High-Speed Digitizers Help -> NI5922 _> input signal conditioning ->Channel Terminal Configuration
Unbalanced differential—This mode is sometimes referred to as pseudodifferential. In this mode, the shield of the input BNC is connected to ground through a resistor. In parallel with the resistor, two antiparallel diodes have been added to protect the programmable gain amplifier, which is limited to ±5 V signals. This mode allows the differential programmable gain amplifier to reject common-mode noise sources from the input signal.
Sorry, can't provide an example on my current system..
Post your code and we can have a look at it.
05-07-2012 07:26 AM
There is an example
open help-> find examples- hardware input..->modular instruments -> ni-scope-> features -> niScope EX Differential.vi
This example showcases the differential feature of the NI 5922. Differential mode detects the difference between the two analog input channels, allowing any signals in common to be discounted. Positive should be connected to channel 0 and negative to channel 1. Configuration for channel 0 will be used for both channels. Only channel 0 should be fetched.
The Single Ended terminal configuration is a non-differential acquisition where the input channels are grounded and independent of each other.
The Unbalanced Differential terminal configuration leaves both channels floating (ungrounded) and each channel is independent of each other.