I have a question regarding the running priorities of the system processes running an Vxworks-based CompactRIOs.
For example, the FTP server of such a CompactRIO seems to be associated with very high priority processes. I have used a utility to measure the CPU consumption of a Vxworks-based CompactRIO. What I can see is astonishing: When I download a large file from the built-in FTP server of the CompactRIO onto my Windows-based laptop, the CPU of the CompactRIO reaches 50% in high priority and 50% in normal priority. This shows that at least one process associated with the built-in FTP server of the CompactRIO has a high priority level.
Unfortunately, this might be a problem for reliability because FTP communications with the CompactRIO are then able to consume the whole CPU and block the acquisition. So, is there any way to lower the priority of the built-in FTP server of the CompactRIO?
The network communication of the FTP server does run at high priority on VxWorks targets. However, this is below the priority of Timed Loops and Time Critical VIs, so there is no chance of blocking acquisition if this critical code is executing in either of these priorities.
| Michael K | Project Manager | LabVIEW R&D | National Instruments |