RB540 in Keyboard Mode

I am trying to use the new RB540 with the keyboard mode with Matlab (Cogent).

Does somebody know how to reset the internal timer to measure for example reaction times?

In keyboard mode, I can access the actual timing, but just from the beginning of plugin the response boxes.



In Keyboard mode, the only way to reset the internal timer is via a light sensor. See its dimensions and specifications.

Also, this support page describes how a light sensor would be used.