This article applies to:
If you are using a computer that does not have a serial port, you can purchase a DB9-USB converter cable for use with devices that use serial communication. We have confirmed that these adapters do work with the SRBox and FOBRS in E-Prime and provide accurate timing even on the slowest of machines.
It is vital that serial-to-USB cables use the latest drivers available. To do this, visit each cable manufacturer's website or use Windows Update to download updated drivers.
Recommended: Prolific cable, model ICUSB232DB25
DB9-to-USB Adapter Brand Compatibility:
|Adapter Brand||Compatible with E-Prime?|
|FTDI||Yes – requires configuration*|
|Belkin||Some reported problems|
*The FTDI brand serial-to-USB adapter requires a change in its latency timer in order to establish a polling rate that will deliver its best results. To do this, plug in the cable, install the latest drivers possible, go to the 'Start' menu, right-click on the 'Computer' icon, go to 'Manage', then 'Device Manager', then expand the 'Ports' dropdown, right click on 'USB Serial Port', select 'Properties', then the 'Port Settings' tab, 'Advanced…' button, and change 'Latency Timer (msec):' from '16' to '1'. Press 'OK' to continue.
Average latencies when using a SRBox or FOBRS with an adapter cable:
|N/A||XKEYS (FOBRS native USB)||10||42.92||52.92||2.44||58||48|
|N/A||XKEYS (FOBRS native USB)||50||42.82||92.82||3.23||99||87|
Timing tests from May 2011. Test results using E-Prime 188.8.131.52. The testing paradigm involved sending a parallel port pulse at the onset of an object from the E-Prime Experiment Station to the E-Prime Timing Station, which waited the specified delay. Then, the Timing Station sent a parallel port pulse to the test device (SRBox or FOBRS) that responded via the adapter cable to the Experiment Station's object's Input Mask. The latency is the recorded RT minus the delay.
Legacy timing differences using the SRBOX with a standard serial port:
|Machine||Operating System||Serial Port Type||Reaction Time Delay (Mean)||Reaction Time|
|Dell 8200 (2GHz)||Windows XP||Standard UART||1.73ms||0.68|
|Dell 8200 (2GHz)||Windows XP||USB-DB9 Cable||1.85ms||0.66|
|Dell 8400 (3GHz)||Windows XP||Standard UART||1.81ms||0.61|
|Dell 8400 (3GHz)||Windows XP||USB-DB9 Cable||1.99ms||0.66|
Timing tests from E-Prime 1.2, March 2006. The ATEN UC232A USB to DB9 serial adapter cable was used. Test results using E-Prime 1.2 with the BBTK triggering a response to the E-Prime subject computer.
To connect the cables and add the SRBox to your experiment:
- Turn your computer off.
- Attach the cables to the SRBox. First, connect the large end of the serial cable to the back of the SRBox where it is marked 'Serial Cable'. Next, connect the power cable to the back of the box and then plug it into an outlet. There is no on/off switch so plugging it in is the only way to ensure that the SRBox is on.
- Connect the other end of the SRBox's cable to the DB9 side of the USB adapter. This is the side that will allow you to screw the two cables together if applicable. Once they are securely connected, plug the USB end of the cable into one of the USB ports on your computer.
- Turn the computer on and make sure that the device is recognized. You may need to use Windows Update to update the cable's drivers so that Windows will recognize it. It should be using COM ports 1, 2, 3, or 4. For specific instructions on how to check your port number, please see below.
- Once you know your port number and have ensured that it is one of the four recognized ports, you can configure E-Prime to communicate with your SRBox. The SRBox can be added by double-clicking the Experiment Object (at the top of the Structure view) to open its property pages, then clicking the 'Devices' tab. Click the 'Add' button and select the SRBox. Click on the small picture of the SRBox to highlight the word 'SRBOX', making sure not to uncheck the box next to it. Click 'Edit...' and make sure that the number after the word 'Port' matches the port number that you saw in device manager. Click 'OK' twice to exit.
- Enable the SRBox as an Input Mask on an object. To do this, double-click on the object on which you would like to add the SRBox as an Input Mask and click on the icon for the object's Property Pages. Once the Property Pages are up, select the 'Duration/Input' tab and click 'Add...' to add the SRBox as the Input Mask.
- Test that your SRBox is responding properly.
To verify your port settings so that you are using the correct COM port, please view INFO: How do I verify the port number being used by the SRBox? .