The MIDI 1.0 Detailed Specification (Document Version 4.2.1 Revised February 1996) has a pretty good description of the relationship between those messages. There are some details to be aware of that you can find in there. The section on Song Position Pointer is very helpful as well. Download the spec here: https://www.midi.org/specifications/midi1-specifications/m1-v4-2-1-midi-1-0-detailed-specification-96-1-4

Yes, you always send 24 per quarter note. You should send MIDI Clock messages nonstop. That way, any device that wants to synchronize can be better prepared to play at the correct tempo as soon as the Start command is sent. When a Stop command is sent, devices stop advancing immediately, but the clock continues to run in the background to keep the tempo at the ready and to keep devices synced even if there are tempo changes while stopped.

Mike.

I tried to infuse just a start and clock signal into my sequenser, but my Roland SC-7 behaves strangely like it try to trigger notes on the clock?
Do anyone have a midi recorder/logger and tell me what is going wrong with the clock?

I could probably not tell what go wrong from the stream.

https://jonasth.github.io/debug/

Maybe my polling of clock "5 ms" not tight enough to give a correct clock timing sent sent over port?

Or have i got it all wrong and clock signal never sent with the actual midiplayup? It is just a separate synch thing sent over a separate cable?
I thought i could send it invoked with song, use it with a midichain setup synths and drummachine/recording device?