Millisecond Forums

Present TTL signals - Port element

By lauriem4 - 8/14/2013


I am trying to write a program that will use white noises that participants will or not be able to stop. In the meantime, I will be recording heart rate and skin conductance. We use AD Instruments in our lab. I'd like to have a mark written on the AD instrument output for every time a noise is started and then when it stops (whether the person stops it or it stops on its own due to timeout). 

I've read the help about how to present TTL signals, how to use the control monitor tool, about the port element, subport and items attribute and downloaded the Oddball Auditory Task from the task library and searched through the forum and it is starting to be a bit clearer to me.

I am still very unsure about one thing though.

How do you determine the sequence to write in the item attribute and the subport attribute (between control and data)? For example, in the oddball task, the item attribute is "00000001" for oddball "00000010" for baseline and "00000011" for response.I thought it was just that for each new signal you want, you increased the binary sequence.

But reading through the forum, the items are sometimes defined by more random sequences so I'm quite lost.

I am also quite confused about the difference between control and data for the subport.

Do I need to plug the AD instrument and use the monitor control tool? Or is there a way to determine this without doing that?

Thanks a lot.


By lauriem4 - 8/14/2013

Sorry when I say "Monitor Control Tool" I actually meant the Parallel Port Monitor Tool

By Dave - 8/14/2013

#1: Whether you use the parallel port's data or control register depends on the external device you use. Those registers represent different pins. You must thus figure out which pins your device expects to be raised (which should be covered in the equipment's documentation) and use the correct register to send them.

#2: The same is true for the actual signal or "item" you send. You are free to send *any* 8-bit binary signal, from 00000000 (0 in decimal) to 11111111 (255 in decimal). Chances are your device expects certain signals to initiate certain actions (e.g. start or stop recording).

#3: A <port> element functions much like any other stimulus element (e.g. <text>) in Inquisit. Item selection and the like works just the same.

By lauriem4 - 8/15/2013

Thanks for your quick reply Dave. I thought it would be something like that. 

Now I'll have a look at the AD Instruments documentation.