FAQ: How can I configure the EyeLink Host PC to accept TTL signals from another device?
TTLs can be received on the Host PC via the parallel port. 

Hardware Setup:
  • All desktop model EyeLink Host PCs have a parallel port and no additional hardware setup is required.
  • For laptop EyeLink Host PCs,  parallel port functionality can be added via a Labhackers USB2TTL8 device or ExpressCard IEEE 1284 Parallel Card (please contact support@sr-research.com for more information).  If using either of these add on Parallel port devices, please make sure the device is connected prior to powering on the Host PC to ensure it's recognized by the Host software.
    • On the EyeLink 1000 Plus or EyeLink Portable Duo, the status of the parallel port devices can be verified from the configurations menu. Go to File Manager on the Host PC (press CTRL+ALT+Q from any tracker screen if the Host application is running), then click the Configuration button (the button that looks like a gear next to the button that starts the Host application) and then click Devices (3rd button from the left). Enable the “Digital In” and “Digital Out” options for the parallel port device -- the Device Name will be "PCI-e_Parallel_Port". Then save and restart the computer.

Host PC Configurations:

To configure the parallel port it is necessary to define which parallel port register the incoming information will be arriving at (see this post on How parallel port signaling works). To do this additional commands will need to be added to the FINAL.INI on the Host PC (see footnote for how to access the FINAL.INI file).

Depending on if the data is coming to either the DATA register (which is typically the case when using a straight through or bidirectional cable) or STATUS register  (which would be the case when using a cross-over cable), the following commands would need to be added:
  • DATA Register

    • EyeLink 1000 Plus & EyeLink Portable Duo Desktop Host PCs:

      write_ioport 0xA 0x20
      input_data_ports  = 8
      input_data_masks = 0xFF
      create_button 1 8 0x01 0 
      create_button 2 8 0x02 0
      create_button 3 8 0x04 0 
      create_button 4 8 0x08 0
      create_button 5 8 0x10 0
      create_button 6 8 0x20 0
      create_button 7 8 0x40 0
      create_button 8 8 0x80 0

    • EyeLink II and EyeLink 1000 Host PCs:

      write_ioport 0x37A 0x20
      input_data_ports  = 0x378
      input_data_masks = 0xFF
      create_button 1 0x378 0x01 0 
      create_button 2 0x378 0x02 0
      create_button 3 0x378 0x04 0 
      create_button 4 0x378 0x08 0
      create_button 5 0x378 0x10 0
      create_button 6 0x378 0x20 0
      create_button 7 0x378 0x40 0
      create_button 8 0x378 0x80 0

  • STATUS Register

    • EyeLink 1000 Plus & EyeLink Portable Duo Desktop Host PCs:

      write_ioport 0xA 0x0
      input_data_ports  = 9
      input_data_masks = 0xFF
      create_button 1 9 0x20 1 
      create_button 2 9 0x40 1
      create_button 3 9 0x08 1 
      create_button 4 9 0x10 1
      create_button 5 9 0x80 0

    • EyeLink II and EyeLink 1000 Host PCs:

      write_ioport 0x37A 0x0
      input_data_ports  = 0x379
      input_data_masks = 0xFF
      create_button 1 0x379 0x20 1 
      create_button 2 0x379 0x40 1
      create_button 3 0x379 0x08 1 
      create_button 4 0x379 0x10 1
      create_button 5 0x379 0x80 0

Make sure there is at least one extra blank line at the end of the file, and then save the file and restart the Host PC software by clicking the EyeLink logo button at the top-left.

To test that the pulses are being received start the EyeLink application and go to the Offline screen (click on the Offline button from the Camera Setup screen). When the pulses are received, the corresponding button numbers will appear at the bottom-right corner of the Host PC monitor.

Note, if the pulses does not need to be associated with button events, then omit the lines that begin with "create_button" in the FINAL.INI file.

*The FINAL.INI file is in the /ELCL/EXE/ folder in the EyeLink partition on the Host PC. The FINAL.INI file can be edited via the file manager software (EyeLink 1000 Plus and EyeLink Portable Duo) or boot the Host PC to Windows (EyeLink II and EyeLink 1000) and edit the file there (the EyeLink partition shows up as another drive when booted to Windows).