Why Does PXIe-1095 Chassis Operate in Different Cooling Profiles with Embedded VST?

Updated Jun 24, 2019

Reported In

Hardware

  • PXIe-1095
  • PXIe-5840

Driver

  • NI-RFSG
  • NI-RFSA

Issue Details

When my PXIe-1095 with embedded vector signal transceiver (VST) PXIe-5840 worked with different host PC through MXI or controller, the cooling profiles of chassis varied, 38 watts and 58/82 watts. What is the root cause of cooling mode options in MAX, from operation system, versions of drivers or MXI compatibility?

Solution

This is not a Windows OS related issue, but related to the RFSA/SG drivers that supports VST. RFSA/SG 17.1 was the first version to add support for System Configuration API and Measurement & Automation Explorer for module temperature and self-calibration date and time. Since PXIe-1095 chassis was released in Nov 2017, any version of drivers before that would not have integrated support of module temperature monitoring in MAX especially for the PXIe-1095, until the next release of RFSA/SG after Nov 2017.
The two-slot VST will draw 80 watts (40 watts per slot) powering from the PXIe-1095 chassis, hence after installing 18.1 RFSA/SG driver, it will in turn enforce chassis into 58/82 watts (by module request) cooling profile instead of 38 watts. That explains why the user has to use the high cooling mode that set automatically in MAX.
Since drives before 18.1 were not designed for the PXIe-1095, NI will not test the behaviors with NI MAX and not do further examinations to the compatibility. Mostly the way these drivers are behaving is letting the user set the fan in low speed (38 watts cooling profile), but it is not consistent.
In summary, if the PXIe controller or host computer is using the most up-to-date PXI Platform Service 18.5 or later, RF-mx 2.5 or later and RFSA/SG 18.1 or later, PXIe-1095 chassis with a VST is forced to operated in high cooling mode for safety reason. If there are no other other cards/modules in the PXIe-1095 chassis that require High cooling profile and the cooling setting is set to Auto.
 

Additional Information

NI will not provide workaround or instruction to use the low cooling profile with VST embedded in PXIe-1095 chassis and do not recommend users use drivers that are not made to support the PXIe-1095 chassis. The importance of using the high cooling mode of any chassis with the PXIe-5840 is to maintain a constant temperature on the VST, not necessarily a low temperature. A constant temperature means at least variance in RF performance from test to test.  The high cooling modes of any chassis help buffer changes on ambient air temperature. This improvement of test stability may be slight if chassis is already in a room with good temperature control; while it may be significant if the chassis is in a large rack with poor ventilation or on a factory floor.