Return vector for points done of check buffer status in onboard program

Question

Background
I am trying to develop a trigger application based on the current position of a contour profile.
I can not use breakpoints as the application is using hydraulic cylinders with analog feedback
for the primary position. In order to make sure the trigger happens relative to the motion regardless
of host load I want to run the application as an onboard program.
My idea is to read the buffer status points done and generate a pulse out as a trigger when the
points done is greater than the programmed trigger point. For example if I want to trigger on the 42
point of a 100 point profile, I would read points done of the main contour buffer. When points done
is greater than or equal to 42, I would generate a short pulse as a trigger.
Question
My problem is, I cannot find the order that the check buffer status VI returns the data to an onboard program
return vector. As I understand it, I need 3 variables to hold the returned data. One each for State, Backlog, and
Points Done. If I set the return vector to 10, does State get stored in 10, Backlog in 11, and Points done in 12, or
is there a different order?
If you could provide the return vector mapping order for all the motion VIs, it would be greatly appreciated.

Answer 1

Hello,
This is a very good question. I checked in the help for the LabVIEW VI, and it does not explicitly state the answer. The VI calls the FlexMotion function "flx_check_buffer_rtn". In the "NI-Motion Function Help" (Start>>Programs>>National Instruments>>NI Motion>>Documentation), the information for the functions states that it "...returns data in the following order: backlog, bufferState, and pointsDone." It also tells you the size of each of the elements. I will be filing a report so that the LabVIEW documentation includes this information in the future. I hope this helps. Take care!
Regards,
Aaron B.
National Instruments