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LabVIEW Bug: The Scan Engine with TC Modules in LV 2019 SP1 with VxWorks target (cRIO-9074)

While working to replace a dead cRIO-9073 on a system using the Scan Engine to read/write various modules (NI 9213, NI 9205, NI 9476) with a cRIO-9074, I found that the system would refuse to connect to Network Shared Variables linked to the Thermocouple channels if Open Channel detection was enabled, and the channel had no TC attached. A Timeout error (-1950678943) is returned when trying to open the variable.


Reading the Help for the configuration panel, it says:

If this box is checked, the NI 9213 returns a zero value and reports an error if it detects an open thermocouple on any channel. This box is checked by default. If you do not check this box, each channel of the NI 9213 independently returns full-scale data and the NI 9213 does not report an error if an open thermocouple is detected.


This is further (at least grammatically) incorrect in that channels that have TCs attached do not throw an error, rather only channels that have no TC connected do. I presume the language "on any channel" was meant to be "for those channels with no thermocouple attached". I confirmed this by attaching a TC to TC0 and trying to read TC0 (which worked) then TC1 (which timed out), then moving the TC to TC1, after which TC1 worked while TC0 timed out.


Ultimately of course, an error should be returned on the Read, but there should be no error on the Open (which of course also prevents creation of the Refnum needed by subsequent NSV commands).





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