The RB Series Response Pads Protocol
Last Revision: May 3, 2004

The information in this article applies to:

• Anyone who wants to understand the protocol used by the RB Series response pads to transmit their information to the host computer.

Summary

The RB Series response pads protocol is a simple yet efficient method of transmitting information to the host. It is directly supported by SuperLab and other programs. It is also emulated on the Lumina MRI response pads and other devices.

Technical Details

The microcontroller inside the response pads keeps an eye on the the status of the keys and sends one byte to the host every time a key is pressed or released. In other words, when a key is pressed, a byte is sent. When the key is released, another byte is sent. Each bit within the byte corresponds to a key.

The built-in microcontroller takes care of debouncing the keys if necessary. This guarantees that, when a key is pressed, one and only one byte is sent to the host instead of a stream.

Starting with the RB-x30 generation (e.g. RB-530, RB-730), the response pads include a new, more advanced protocol called XID that provides built-in timing and other features.  However, Cedrus remains committed to including the RB Series protocol in its products because it is supported by a number of products such as Inquisit and Presentation.