Millisecond Forums

Cedrus response box support with Inquisit 4

By KJantzen - 6/26/2014

I am using a cedrus response box 530 to collect responses and to trigger EEG equipment.  It is important that I only get a single ttl trigger for each button press but it seems that Inquisit is putting the response box into double pulse mode where I get a ttl trigger when the button is pushed and a second when the button is released.  Is there any way to control or alter this in Inquisit?
By Dave - 6/26/2014

I am not aware of any way to alter an RB's accessory connector behavior directly from Inquisit -- at least not at present. However, if I am not totally mistaken, the accessory connector's behavior -- including pulse mode -- can be configured using Cedrus' "Xidon" tool:

Or are you suggesting that Inquisit *alters* the pad's configuration to double-pulsing?
By KJantzen - 6/27/2014

Yes, it seems that Inquisit does alter the response pad to double pulsing.  I used in house matlab code to alter the mode of the response pad to single pulse mode.  After verifying this mode using in my EEG acquisition software I ran my inquisit code and when I responded to stimuli I found that the button box was once again in double pulse mode. 
By Dave - 6/27/2014

Thanks for the clarification. Then all I can do for the time being is file a bug report so this gets fixed in the next release -- at the very least, Inquisit should not change the pad's configuration inadvertently.
By Dave - 6/27/2014

One more question, if I may: Which Inquisit version have you been using? If it is not up-to-date ( v. at the time of writing), could you please confirm the issue w/ the latest release? Thank you.
By erikb - 6/27/2014

Could you please provide me a copy of the script you're using?  

I know that Inquisit doesn't contain any code that would set it to double pulse mode (a13).  However, if a response box is used as a stimulus via the <xid> element  we do set the lines to General Purpose (a10), the direction to output (a4), and optionally set the pulse duration (ap).  I haven't confirmed, but we may also set that if you just have an <xid> element in the script, but that would be an easily fixable bug.

If you just have a single XID device used just as an input device (and you don't need to scan for a specific one or alter the pulse duration) you can just specify /inputdevice = xid in <defaults> and omit the <xid> element and Inquisit shouldn't touch those settings.

Thanks and Enjoy,

By seandr - 6/30/2014

FYI - I've just posted an updated version of Inquisit 4.0.6 that should fix this problem. You can download and install from our download page:
You'll have to uninstall your existing copy of 4.0.6 before you can install this one.
Give it a whirl and let us know if the problem persists.


By KJantzen - 7/1/2014

Thanks for the responses and fixes.  I will give them a try.