Using the RB-x30 Response Pads with E-Prime
Last Revision: November 8, 2006

The information in this article applies to:

• Owners of an RB-530, RB-730, RB-830, or RB-834 response pad who want to use it with E-Prime

Summary

A built-in feature in the RB-x30 response pads gives them the ability to emulate the PST Serial Response Box Model 200A shown below.  This feature enables the response pad to seamlessly work with PST's E-Prime software. This document shows you how to enable this feature.

How It Works

Two features make it possible to connect an RB-x30 response pad to E-Prime.

The first one is the USB driver that comes with the response pad. A driver is a small program that is needed by most USB devices (other than keyboards, mice, and so forth). When installed, the RB-x30 driver makes Windows think that a serial port has been installed. This way, E-Prime does not have to worry about the details of connecting to a USB device -- it simply thinks that it is communicating with a serial port.

The second feature is the built-in PST Serial Response Box Model 200A emulation. This saves you time by not having to write E-Basic code since E-Prime already knows how to "talk" to the Model 200A.

Before you proceed, please make sure to install the USB driver if it has not been done already.

Updating the Response Pad's Software

Unfortunately, on models produced prior to 2005, a bug in the response pad's built-in software prevents the response pad from working correctly with E-Prime. An update need to be performed (only once) before you proceed. Please click here to perform the update.

Enabling SRB Model 200A Emulation

Placing your RB-x30 response pad in SRB Model 200A mode is a simple matter of flipping a switch or two.

Take a look at the back of your response pad, illustrated below. You will find four things, from left to right: the Accessory Connector for connecting to external peripherals; a set of four switches; a small green LED (light); and the USB port for connecting your response pad to the computer.

When shipped, all four switches are in the down position. This is the XID mode running at 115,000 baud. To place the response pad in SRB Model 200A mode at 19200 baud, you need to flip switch 1 (the leftmost one) UP. You can change the baud rate (speed) by flipping switch 3. The following illustrations show the only switch combinations that apply for emulating the SRB Model 200A:

The baud rate that you select should match the baud rate setting in E-Prime. If you are not sure which one it is, try both combinations.

IMPORTANT: An RB-x30 response pad "reads" the switch positions only when it is first turned on. After you flip a switch, you must unplug the USB cable from the response pad, wait a few seconds, and then plug it back in.

Which Switches Are Emulated?

The SRB Model 200A has five push buttons and voice key. Here is how they correspond to the various RB-x30 models:

Using Your Pad With E-Prime

To use an RB-x30 response pad with E-Prime, you need to follow that product's instructions for using the PST Serial Response Box Model 200A.

Because the RB-x30 response pads are USB products, they will not work with MS-DOS programs like MEL Professional or the PST SRBOX utility program.

Known Issues

There are only two known issues:

1. When you run an E-Prime experiment, the first "response" from the response pad will likely be the wrong one and will occur without the participant pressing any key. We suggest that you insert a code at the start of the experiment to get a response and then just ignore it.  All subsequent responses from the participant will be the correct ones.

2. In some instances, it is possible that E-Prime will not "see" the response pad after you turn on your computer. Another symptom might be that the mouse cursor will start moving erratically. The solution is to unplug the USB cable from the response pad before turning the computer on, and then plug it back after the computer has completed its startup. The reason is this: the RB-x30 response pads work by emulating the PST Serial Response Box Model 200A, which in turn works by sending a constant stream of bytes to the computer all the time. When starting up your computer, Windows tries to be smart and checks all the computer ports (serial, parallel, USB). When it sees this constant stream of data coming, it thinks that the computer has a mouse connected! Unplugging the USB cable during startup gets around this.

3. Often, Windows will automatically have the USB driver emulate a port that is higher than COM4, e.g. COM7 or COM8.  E-Prime can only use COM ports 1 through 4.  See the document Determining or Changing the USB Driver's COM Port Setting for assistance in reassigning the USB driver's COM port number.