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Cedrus Responsebox doesn't working

I tested two RB series response box in two different MAC OS (OS 10.10), but got same error messages.

Traceback (most recent call last):
File “/Temp/test”, line 110, in
if t >= 0.0 and buttonBox.status == NOT_STARTED:
File “/Applications/”, line 433, in getattr
return getattr(self._impl, attrname)
AttributeError: ‘ResponseDevice’ object has no attribute ‘status’

Current solution : use 1.83.4
I tried 1.84.2 with pyxid copied from 1.83.4 but still doesn’t work.
It seems the problem is related to new pyserial or pyo.

Hi, I’m a newish Psychopy user and I’ve tried what you suggested for a similar Cedrus response pad problem. However, I got this error message:

buttonBox.status = NOT_STARTED
NameError: name ‘buttonBox’ is not defined

I’ve never used Cedrus response boxes before and certainly not in PsychoPy, so I was wondering if you could give absolute newbie me some (detailed and written for dummies) advice for implementing the response pad through the builder view :slight_smile:

Dear cnsla and Irina,

I had a similar problem a little while ago, I asked Cedrus, and this is what they told me:


Here’s the background story.

We use USB chips manufactured by FTDI ( There are two types of drivers available: VCP and D2xx. VCP is the virtual COM port driver, the one that emulates the serial port. It is convenient because all the software written to communicate with a serial port will continue to work.

However, the precision of the VCP driver is in the 5-10ms, with some variability. We have spent considerable time on our I/O subsystem to switch from VCP to D2xx drivers because we can then obtain a 2ms delay that is jitter free.

On Windows, FTDI has managed to have both types of drivers coexist. But on non-Windows systems, VCP and D2xx cannot coexist — it’s one or the other, but never both. This explains why it’s not working on Mac, Fedora, or Debian.

In summary: you need to make sure that the VCP driver is not installed.


So if you are using the latest generation of Cedrus boxes, the simplest solution is probably to use them with Windows only. Unless of course you want to mess with your system drivers, which you shouldn’t, unless you really know what you are doing.

Hope this helps,