OnSong has the ability to send MIDI events to compatible devices based on the tempo provided for each song in your library. This can be done in one or more of the following ways depending on the requirements of the device. These can be configured by opening the Utilities Menu by tapping on the gear icon in the Menubar and choosing Settings and then MIDI Settings. Locate the Sync section and choose one or more of the following methods.
This send a MIDI signal 24 times for every quarter beat and is only recommended if you have a hard wired connection to your device as wireless MIDI results in too much latency for an accurate reading.
OnSong can convert the tempo of the songs into control changes. While this is not in the MIDI standard, it is frequently used by some devices as it does not require low latency to transmit. This will send one LSB (least significant bit) to represent tempos between 0 and 127, and MSB (most significant bit) to allow for tempos in multiples of 128. For instance, it would send 160 BPM as MSB 1 and LSB 32. You can configure the channels this is sent on as well as the control changes to be sent.
This option will send a MIDI signal for every BPM as specified. This is akin to tapping a foot switch to dial in the tempo on a device. You can configure the channels and the MIDI events that are sent.