viSci

Greetings - After much experimentation I have concluded that the standard waveform pulse and transient measurement vi's in LabVIEW are not adaptive enough to handle analysis (High, Low, Tf, Tr and Pulse width) for a generalized pulse that can be rectangular or in some cases triangular with zero pulse width. I am thinking that the solution might be a type of piecewise linear regression. Has anyone accomplished this without making assumptions on the number of linear segments in the waveform? Is there another way to try to model this?

Hello again - Well its been a year so I wonder...have you been able to do any 2019 or 2020 LVRT testing on the messenger libraries yet?

Pretty easy to setup and keep running. If you give me more specifics on your application I could provide more relevant information...

https://www.rti.com/products/benchmarks

Yes I have been using it quite a bit on a roadway monitoring project with 50 cRIO's. I use it to handle all of the cRIO system state and tag data publishing. We are still in the early stages of testing but it seems to be working very well. The LabVIEW version of RTI DDS is a subset of its full capability. RTI has been slowly adding features but it still does not support basic things like events. Judging from the forum posts, the toolkit is largely unknown in the LV community. I think if more people adopted it, it would garner more love and attention by RTI.

It is disheartening for those of us who develop for the cRIO to see NI come out with a cool product like systemlink but in a misguided marketing strategy have totally ignored those of us toughing it out in the trenches trying to develop secure and robust DDS capability for the cRIO. Even basic stuff like cRIO image management and software deployment, which systemlink handles nicely have been bundeled exclusively in the prohibitively expensive package that NI is trying to sell to electrical utilities.

It's not exactly native but the RTI DDS api has been included in the past few LabVIEW releases.

Just checking in to see if you have been able to do any LV2019 testing on this issue yet...

Yes it appears to get hosed up inside the TCP Listener Actor. The funny thing is that I can compile an exe and run on my cRIO just fine, it is only via the IDE that there is a problem. This has been working with LV 2018 for many months without issue so it appears something has changed in LV2019.

Since upgrading to LV 2019 I am seeing issues with an existing application running on a Linux based cRIO. The deployment process itself seems to be much slower and this initial section of code is causing the cRIO to disconnect from the development system. When the execution gets to the TCPEventMessenger Create subvi I get this popup and execution is aborted. Any thoughts?

Just in case someone else stumbles across this problem... It turns out the the cRIO-9056 has TSN capability built in so it will automatically try to slave the AI sample clock to a 1588 master if one is present on the network. In my case the master clock is not disciplined which wrecks havoc on the AI HW timing as it is only software based for the purpose of syncing the cRIO to the PC's clock for uniform relative accuracy. The solution to the is to use an obscure DAQmx property as follows... Add a DAQmx Channel Property Node to the task, select the General Properties >> Synchr

At my wits end with this... When 1588 timesync is running it appear to interfere with DAQmx AI timed tasks. I am seeing strange errors -200284 (buffer underrun) or -209836 (The devices in your task cannot be synchronized) when I start my DAQmx task with 1588 engaged. When I disable the 1553 master on my network or remove the 1588 driver from the cRIO everything works correctly. To simplify testing I am using a DAQmx example - Thermocouple - Continuous Input.vi to do my testing. I do not have any HW sync modules just plain C series AI modules so there should be no attempt to perform any

Curious to know more about the performance issues you were seeing with DAQmx on the cRIO. I would think it should be fairly high performance.

along time ago I ran across an interesting paper by Monnie. https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=664322 I used some of his ideas as the basis for this... http://viscience.com/blog/portfolio-3/

BTW, which websocket library would you recommend for command-reply use cases on a Linux RT target?