List of electrical characteristics of single collision domain segment "slow speed" network buses: min.
39.216 kbits/s Open collector variable up to ~150 kbit/s (depends strongly on physical setup) The number of nodes can be limited by either number of available addresses or bus capacitance.
None of the above use any analog domain modulation techniques like MLT-3 encoding, PAM-5 etc.
PSI5 designed with automation applications in mind is a bit unusual in that it uses Manchester code.