FORP
The fORP USB interface emulates a USB keyboard. USB keyboards have some timing jitter due to the HID polling algorithm, but the fORP tries to minimize this by requesting a 1ms polling interval. In our experience, the reaction time of subject responses can be measured to about 1ms using the fORP USB interface. However, if you need even better precision, or if you have legacy equipment which needs a TTL output, you can connect to the auxiliary connector on the back of the fORP. This MDR-36 connector, described on the CurrentDesigns website, provides TTL outputs for all button presses and scan triggers, as well as a serial interface. Vladimir Vildavski built a cable to break-out the most useful TTL outputs to a simple male DB-9 connector. We usually keep Vladimir's cable in place, so if you can use DB-9, please do to avoid the need to be swapping cables. The DB-9 cable details (from Vladimir's notes):
fORP Digital Output Cable Pinout. MDR36 male to DB9 male. Note 1. The fORP digital signals are floating high in the "0" state, therefore the pull down resistors of 4.7 KOhm connecting signal pins to the GND are required at the receiver device. Note 2. The Left/Right labels on response pads do not correspond to the fORP documentation. The left/right designation of the response pads in the first column of the table follows the fORP docs. Buttons on MDR36 DB9 male DB9 female NS bit Response Pads from fORP to PD or NS NS splitter (DIN event) ---------------------------------------------------------------------------------------------------------------- Blue left pad 22 3 3 2 (DIN3) labeled RIGHT at CNI Yellow left pad 24 4 - - Green left pad 26 6 - - Red left pad 28 7 - - Blue right, or cylinder 30 1 1 0 (DIN1) labeled LEFT at CNI Yellow right, or cylinder 32 2 2 1 (DIN2) labeled LEFT at CNI Green right, or cylinder 34 8 - - Red right, or cylinder 36 9 - - GND 7 5 5 -