Sending event markers in E-prime to Nirx through cedrus c-pod

Hello everyone,

My colleagues and I are designing an experiment combining different psychological tasks with functional near-infrared spectroscopy (fNIRS). We have recently acquired a Cedrus C-pod to send event markers in E-prime to Nirs software.

I’m writting to you because we’are very lost. We have not successfully sent any event marker. Here (, we saw some e-prime examples but we don’t know how to modify the InLine Code to sent event markers when the subject responds using the keyboard instead of when a stimuli appears. We need to register the key responses.
We have programmed a version of the Iowa Gambling Task in which participants have to respond to the decks A, B, C and D pressing 1, 2, 3 and 4, respectively, so we need to mark each response. I mean, we need four different triggers, one for each deck choice. In E-prime, we also tried to set the ‘Task Events’ with Keyboard.Press as Event, WriteByte as Action and RESP as Parameter (it worked with another StimTracker) but it was like C-Pod does not receive any signal. We still do not know how to control c-pod with E-prime.

So, our corcern is, how do we have to modify that inline code to send markers when the answer key is pressed?

We hope you can help us,

Thank you for your attention,


Hello Pilar, the question is rather specific to E-Prime. You might have better luck asking it on the PST forums.

Side note: a Cedrus response pad combined with an m-pod might be a better solution for you than c-pod. That way, key press information is automatically sent out without any need to program in E-Prime. See the Guide to Integration Solutions.