Considerations When Migrating from PXIe-5840 to PXIe-5841

Updated Apr 27, 2023

Issue Details

I’m interested in migrating from the PXIe-5840 to the PXIe-5841.  Are there any differences in behavior that I should be aware of?


The behavior changes are categorized based on whether you are using an NI LO source such as the PXIe-5653.  The available hardware migration paths are: PXIe-5840 to PXIe-5841, PXIe-5840 with PXIe-5653 to PXIe-5841 with PXIe-5655, and PXIe-5841 to PXIe-5841 with PXIe-5655.  Below are the known differences for each path.

PXIe-5840 to PXIe-5841 Behavior Changes
  1. If you are currently using the PXIe-5840's RFSG auto offset behavior when signal bandwidth is set, the PXIe-5841 will be doing a different amount of auto offset.  To determine the configured frequency offset, check the value of the Upconverter:Frequency Offset property.
  2. There are a number of differences in specifications between the PXIe-5840 and PXIe-5841.  Review the specifications documents for each device in the related links to learn more about the differences.
PXIe-5840 with PXIe-5653 to PXIe-5841 with NI-5655 Behavior Changes
  1. Configuring Clock Source to "RefIn2" option is not supported by the PXIe-5841 with PXIe-5655 configuration.
  2. Unlike the PXIe-5653, the PXIe-5655 is not supported as an independent module. It is only supported when associated with a PXIe-5841. 
  3. Calling Self Cal on PXIe-5841 with PXIe-5655 will also calibrate the LO Alignment and there is no need for you to perform any additional LO Alignment (the PXIe-5840 with PXIe-5653 expected the user to perform an external LO Alignment).
PXIe-5840 to PXIe-5841 with PXIe-5655 Behavior Changes
  1. If you perform self-calibration on a PXIe-5841 with PXIe-5655, the composite module will be calibrated (including the path for the cross-switch); however, the path for the Internal LO will not be calibrated.  The rationale behind this behavior is to minimize execution time of self-calibration. 
Note that the "niRFSG Get Self Calibration Date and" and "niRFSG:Last Self Cal Temp" will return appropriate values based on your model. In NI-MAX different values will be displayed for these attributes if your PXIe-5655 is associated with a PXIe-5841 versus just a PXIe-5841 as shown in the below figure.
PXIe-5841 and PXIe-5655 Self Cal
Figure 1. NI MAX Self Calibration data of a PXIe-5841 without PXIe-5655 (left) and self calibration data of a PXIe-5841 with an associated PXIe-5655 (right)