On this UR5e ticket the video and message belong to one occurrence, but I have no preceding request trace; how should I ask the seller what maintenance needs to capture next?
Ask them to name the expected request source and relevant time window for that message. The technician should not have to guess which program supplies a confirmation merely to collect useful evidence.
Seller has identified the PLC request source; maintenance is checking whether the retained history covers the requested period before arranging another capture.
Did they also identify the fitted receiving arrangement in their explanation? A generic PLC signal name may still need the physical context from your occurrence.