Triggering TMS via E-prime
The following example shows an E-prime experiment in which TMS is triggered via a parallel port at the onset as well as at at varying stimulus onset asynchronies (SOAs) of the target stimulus.
The monitor refresh rate dictates the duration of all objects in the procedure so computing the frame rate and using its multiples for durations will allow the experiment to run smoothly.
Logging TimeAudit for all items whose duration and correct onset are important for the experiment is crucial. This allows to rule out trials in which something appears later (and, as a result, when TMS trigger is not activated on time) due to internal computer error. See E-prime documentation on timing issues. PreRelease is a fix for many timing issues in this software and is worth looking into.
The computer/TMS should be tested with an oscilloscope to ensure that the PC triggers TMS as desired. On-line monitoring of TMS triggers with an oscilloscope is also frequently practiced.