Open collector output

This is an output circuit that uses a transistor, in which the collector serves as the output terminal.
The transistor acts as a contact, so this is referred to as a contactless output.
Typically, the collector terminal is pulled up externally to convert the signal into a voltage signal.
With voltage pulse output, a fixed voltage level is provided, but in the case of open collector output, users need to supply their own power source; however, the advantage is that the voltage level can be freely set.
The signal is output through a single line, with the potential difference between the signal line and GND representing the signal.