Maximum transmission distance for RS-232 computer cables

Abstract

Results of a study to establish guidelines for maximum cable lengths in a variety of typical RS-232 applications are presented. Even when worst-case conditions and 20% safety factors are included, the study indicates that cable lengths can often be used which are much longer than those suggested by the EIA standard. Maximum utilization guidelines are recommended for all systems running at partial utilization. Cable length is dependent on the cable capacitance and crosstalk, and on the driver and receiver electronics. Cable lengths are decreased if the system is subjected to external noise or ground loops. Because of the negative impact of external noise, shielded cable is recommended in most RS-232 applications.<>