# control over DB9 pins

**URL:** <https://psychtoolbox.discourse.group/t/control-over-db9-pins/424>\
**Category:** Uncategorized\
**Created:** [March 8, 2013, 12:18am UTC](https://psychtoolbox.discourse.group/t/control-over-db9-pins/424 "2013-03-08T00:18:21Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Allen\_Ingling](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Allen\_Ingling](https://psychtoolbox.discourse.group/u/Allen_Ingling)\
**Post date:** [March 8, 2013, 12:18am UTC](https://psychtoolbox.discourse.group/t/control-over-db9-pins/424/1 "2013-03-08T00:18:21Z")

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I have an acquisition device that can code events by the simultaneous (binary) activation of TTL pulses across the 8 non-ground pins of a DB9connector. ie. A TTL on pin-1 can code a specific event a TTL on pin-2 can code a different event and so on and so forth such that a TTL sent on all 8 active pins would correspond to a 255th unique event.   
The question I have is: how to I get pin-level access to the DB9 cable? I'm working on a new mac with a usb to serial adapter and as far as I can tell, all 'data' gets sent out pin-3.   
Can this be handled in MATLAB/psychtoolbox or will I need to make a custom device?  
Thanks!  
Gideon