Script sends 29-bit extended frames sometimes, and standard frames other times.

[Howard Shaw]

I've purchased a couple of CL1000s from "CSS Electronics". I'm communicating with a device using CANopen protocol, and am writing a script to mimic several messages. If I call can.sendframe() from one place in the code it always sends 11-bit standard frames (which is what I want), if I call can.sendframe() from a different place is always sends 29-bit extended frames (which I don't want). I can't work out why and I can't see how to force standard frames? If I use the custom "Frame Sender" then I can choose standard frames and everything is as I expect. Here is a screenshot of the frames, lines 2 & 8 are sent from line 153 of the script. Lines 4, 5, 6 are sent from my script's tick() function.

I've uploaded the script as a .TXT but the file is really a .JS
script.txt

Any help would be most appreciated.
Thanks,
Howard.