https://docs.emtronaustralia.com.au/engine-management/config/channels/speed/index.htmlNormally these are frequency based inputs and should be connected between Digital Input 1 - 8. The ECU can can read a frequency range on these input from 0Hz - 25kHz (25000Hz). The following Speed Options are available: Left Drive Speed. Right Drive Speed Left Drive Speed 2 Left Drive Speed 2 Left Ground Speed Right Ground Speed Drive Speed Ground Speed Turbo Speed 1 Turbo Speed 2 Input Shaft Speed Tail Shaft Speed Sources The following channel assigns are recommended.Hugoen-us