PsychoPy loops parametrisation of 2 images variables

[Asma_Ben]

PsychoPy 3
Dear PsychoPy community ,

I am setting up an experiment with an image variable :
My loop go like this :
Cue + Fixation Cross + Image + ITI ( Interstimulus interval).

I have two variables of images :
Image 1 : Trigger pulses starting at 0ms ( Inner loop 1 )
Image 2 : Trigger pulses starting at 500ms ( Inner loop 2 ) ,

I put an outer loop grouping these two inner loops and woud like them to run randomly.

Tha image file contain 50 images, I want half of them to be set up with pulses starting at 0 and another half starting at 500ms, all in a randomised way.

Issue : My images are either displaying twice with both of trigger pulse’s types or running in a sequential loop showing images without randomization.

Is there any way to randomise my images ( linked to the trigger pulses) , OR randomise the trains of pulses starting time within the images since it is the same images files .

I have tried both of theses :
https://www.psychopy.org/builder/blocksCounterbalance.html

Random routines

OK, you need to insert a fourth loop, that surrounds all three of the existing loops. This outer loop will run three times, but on each iteration, only one of the inner loops will be allowed to run. So: Insert that fourth loop, set its nReps value to 3, and don’t connect it to a conditions file. In the trial routine, insert a code component (from the “custom” component panel). In the “Begin experiment” tab of that component, insert the following code, which will run once at the start of the e…

Find attached my experiment :
The final goal is to randomise the starting time of the pulses trains within one block.

PS: By Triggers or pulses I mean here paralele port component signal to start a trains of pulses on the TMS .
Thank you in advance for helppp.

.