Sending a Pulse to another device

[rothers27]

[edited by moderator]
Hello and thank you to anyone who can help! I need to send a pulse from MediaLab at the onset of a picture presentation (which is a file) to another device. I just need to send a binary 1 or 0. The other device just needs to know when the onset of the picture was for recording physiology data.

Thanks! MR

[jarvis24]

Here is the section from the user's guide on TTL signals:

To communicate with external computers or hardware you can send out a signal from MediaLab at the onset of any item. The signal can be a byte value (any integer from 1-255). You can send the signal to any port address you like. Make sure you use the decimal value of the port—not the hex value. For example, the port address of the parallel port on most systems is 888 (or 378 in Hex). Finally, you can send the signal for any duration you like before it resets to 0. Specify these three variables in the parameters field like so:



For example, say you present an image item for 5 seconds and at its onset you want to send a signal of 255 to port 888 for 10ms. To present it for 5 seconds, you would use parameter value of (d5). To add the TTL signal at its onset, you would add:

(d5,<255:888:10>)

Note that MediaLab now comes with the I/O test utility created for DirectRT. It should be located here:

C:\MediaLab\Utilities\TTL\IOTest.exe

You can use IOTest.exe to test whether your external hardware can send and/or receive TTL signals from any given port. More detail regarding the I/OTest utility can be found in the DirectRT user's guide or online here:

www.empirisoft.com/directrt/help/directrt_samples_of13_ttl_signals.htm