olemus
jadaliidese füüsilise taseme standard

ülevaateid
https://www.omega.de/temperature/z/rs232standard.html

https://www.codrey.com/embedded-systems/rs232-serial-communication/

https://ru.wikipedia.org/wiki/RS-232

http://www.tscm.com/rs-232.pdf

http://bitsavers.trailing-edge.com/pdf/datapro/communications_standards/2740_EIA_RS-232-C.pdf