A “fiber to copper” box translate and enhances the pulse event from the scanner received over fiber optic cable to a longer and stronger signal to the button box, which is then presented to a task computer as a key press from the USB source (likely = but previously ^).
This simulated keypress is used to start an fMRI task. See Triggering Task Start.
Some time in 2023-07 ⚠️ not all pulses were correctly converted to keyboard pushes on Prisma 2. As a result, a MR acquisition could have started before the task.
In 2024-12, ✅ the TTL pulse hardware issue was resolved. The QC protocol includes confirming the “EPrime” computer receives all expected TTL-to-= pushes during the phantom EPI.