Control multi dynamixel AX-12 with LabView

Question

I need help controlling 2nd Dynamixel AX-12 from LabView based on "Dynamixel Sync Write Example" code.
We used one USB2 dynamixel to control one dynamixel ax-12 from Labview. It worked well.
Recently I added another ax-12. The two ax-12 are in series. USB2dynamixel is set to TTL. The Labview code generated dual control front panal automatically. Controlling one unit is good. But controlling the 2nd ax-12 is a problem:
The ID seems incorrect according to USB2dynamixel chart: the unit next to the USB should be #0, the one in series with #0 should be #1 and so on. On my setup, I couldn't find a correct ID associated with the unit next to the USB. The one in series with it is #1. Only #1 responds correctly to front panel control.
When click "run" 1st time ax-12 #1 will rotate according to set positions. click "run" again, the other ax-12 will rotate according to #1's set positions, not its own positions. The other unit's ID can be set any number, and results are the same.
Has anyone used the same LabView code to control more than one ax-12 with USB2Dynamixel? Anything I have missed? Appreciate your inputs.
Attachments:
front.PNG ‏53 KB
block.PNG ‏38 KB

Answer 1

Thanks, Drew
You are correct that the code is from NI example less while loop. I did repeated runs, results are the same as two single runs.
I just traced the executions and recorded header and checksum parameters for ID #1 and #2 for debugging. I placed two sets of positions to separate ID#1 and ID #2:
         Control      Dial      Position      Manual pos
ID#1      0           off         60              160
ID#2      1           on        100             200
There is only one set of header and checksum value being passed in the program. That might explain only one set of position (ID#1) was set, the other one (ID#2) was ignored.
Does that make sense?
Anne
Attachments:
111026 dynamixel.pdf ‏198 KB