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Chronos Response Device

edited February 2016 in OpenSesame

Hi Guys.

Has anybody tried to use PST's Chronos System ( with OpenSesame? AFAIK the predecessor (Serial Response Box) worked with OpenSesame. We are thinking about buying some of these devices, but they are useless for us if they won't work for OpenSesame experiments...



  • edited 3:46AM

    Hi Timo,

    I suspect that the old SR box plug-in should do the trick for the Chronos system as well. Is there a way for you guys to try out the system before purchasing it?



  • edited 3:46AM

    Unfortunately we can't try it out before. No lab i know has bought it. :(
    That's why i hoped for someone from the community here....

  • edited 3:46AM

    Hi guys,

    To make it more difficult; another guess here.

    I think the chronos hardware will not work with the SRbox plug-in in OpenSesame. The chronos device has so many extra options (like LED, audio in, audio out etc) that is seems impossible to me to cramp this all in the SRbox protocol (which is basically sending and receiving 2 bytes).

    But I’m not a 100% sure because we do not have the chronos hardware and I can’t find anything in the latest version of E-Prime or on the internet about the protocol/device type.

    Best, Jarik

  • edited February 2016

    Thank you for your thoughts... That's what i feared. :-?
    I also searched for the protocols on the internet, but fpound nothing helpful. Seems PST doesn't want to share too much information. :)

  • edited 3:46AM

    I agree with @Jarik: I don't see how all the Chronos' functionality (especially voice streaming) can be handled by the original SR Box protocol.

    Personally, I wouldn't buy this device. I'm sure it's nice and all, but PST will probably never reveal the protocol, which means that it's tied to E-Prime (until guys like @Jarik reverse-engineer it like they did for the SR Box). Why are you interested in the Chronos specifically? There are other response boxes that do have an open protocol. For example, Cedrus has a Python library for their devices.

    There's much bigger issues in the world, I know. But I first have to take care of the world I know.

  • edited 3:46AM

    To be honest: it was just convenience... I knew the SR box from my former lab and was happy to be able to stay with it while using OpenSesame.

    However, i am very, very interested in your thoughts on alternatives like Cedrus! I never heard of it, but open protocol and OpenSesame compatibility are great arguments.

    I would love to benefit from your experiences, so any thoughts on alternative resonse boxes are very welcome! :)

  • edited February 2016

    I've personally never used Cedrus, but they seem ok, although expensive. I mainly use either the srbox-compatible device that @Jarik builds for his department (but these are not for sale I think) or a Boks. The Boks, a project that I was involved in, was supposed to become a low-budget, high-quality, open-source response device. The device itself works great, but we never got it into production. (We grossly underestimated the practical difficulties of doing a project like this.)

    I still have a few Bokses lying around though. If you're interested in one, send me an email.

    There's much bigger issues in the world, I know. But I first have to take care of the world I know.

  • edited 3:46AM

    Hi folks,
    My lab just got a PST chronos and I have been literally pulling my hairs to make it work. But all in vain. Is there anyone who has got this right?

  • edited 3:46AM

    I think your best bet will be to ask if the PST support staff can give you an example of how to use the device in Python. Once you have that, you could write a simple inline_script to use it in OpenSesame.

    The website lists E-Prime 2.0 as a minimum system requirement. But I'm sure the device must be able to interface with other software as well. (I'm less sure the PST people will tell you how, though.)

    There's much bigger issues in the world, I know. But I first have to take care of the world I know.

  • Hii, could anyone tell me how to command chronos using ebasic in E prime 2

  • Hi enriqueravi,

    E-Prime has their own support section on
    In contrast to OpenSesame, E-Prime is a non free (and non open-source) program, so they should give you some support...


  • bumping this question up again.

    The lab I am working in is trying to get a SR box that works with opensesame and it looks like the original (classic) five-button SR box has been discontinued in pstnet. Does anyone have ideas as to what alternative key boxes can replace the original SR box and are also compatible with the opensesame plugin?

  • How about a joystick? I think joysticks/ gamepads are fine response devices. Of course they don't have the temporal precision of a dedicated response box, but in most cases that doesn't matter anyway. (Because the extra variance introduced by the response device is negligible compared to the natural variance in response times.)

    Other than that, you're probably stuck with expensive devices like those made by Cedrus.

    There's much bigger issues in the world, I know. But I first have to take care of the world I know.

  • Thanks, Sebastiaan for your answer!

    Unfortunately, the temporal precision is why we are looking for a response box in the first place (for collecting RT data). It sounds like we are very much stuck with few expensive choices. Would Cedrus box work with the SRbox plug-in currently provided by Opensesame? Or is it likely that I have to undergo further tweaks to the code to make it work?

  • I doubt that the Cedrus box will work with the SR Box plug-in, because that would mean that they have emulated the protocol used by PST (and why would they?). So if you want to use it, which is possible, you'd probably have to write an inline_script that uses the Python library provided by Cedrus. And this could even be turned into a plugin, so that it becomes easier in the future.

    There's much bigger issues in the world, I know. But I first have to take care of the world I know.

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