Knowledge Base

Problem

A user wants to send TTL pulses to a third-party system (e.g., Doric optogenetics system) triggered by the 'In Zone' variable in EthoVision, but the TTL output does not appear to fire or triggers the wrong output channel.

Details

When using the USB I/O Box with EthoVision's Trial & Hardware Control to send TTL pulses based on zone occupancy, users may configure the correct logic but assign the output to the wrong TTL channel (e.g., TTL output 2 instead of output 1), resulting in no signal reaching the connected device. This is a configuration issue within the custom hardware interface. Affects EthoVision XT with the Trial & Hardware Control module.

Solution

1. Open EthoVision and navigate to the Hardware section for your experiment.
2. Open the Trial & Hardware Control settings and locate the rule that should trigger TTL output based on the 'In Zone' variable.
3. In the rule action, check which TTL output channel is selected (e.g., TTL output 1 vs. TTL output 2).
4. Confirm which physical output pin on the USB I/O Box is connected to your third-party device. Match the software output channel to the physical connection.
5. If the signal is going to TTL output 2 but the device is connected to output 1, either rewire the physical connection or change the rule action to use the correct output channel.
6. Test the output during a short trial to confirm the TTL pulse is received by the external device at the expected times.
7. Refer to the USB I/O Box pinout documentation to verify output channel assignments.