National Instruments PCI-8430 - Serial Port Information

SerialPortInformation
ThefollowingtopicsdescribetheRS-232,RS-422,andRS-485
standardsandexplainsomeoftheissuesinvolvedwiththesetypesof
serialcommunication.
RS-232
RS-422
RS-485
SerialCommunicationIssues
DuplexArchitectures
FullDuplex
HalfDuplex
RS-485Termination
BiasResistors
RS-232DTEversusDCE
ThefollowingtableliststhefeaturesoftheRS-232,RS-422,andRS-485
standards.
RS-232,RS-422,andRS-485Features
Feature RS-232 RS-422 RS-485
Typeoftransmissionlines Singleended Differential Differential
Maximumnumberofdrivers 1 1 32
Maximumnumberofreceivers 1 10 32
Maximumcablelength 50ft 4,000ft 4,000ft
Maximumdatarate 20kbytes/s 10Mbytes/s 10Mbytes/s
MaximumCMV ±25V ±7V +12to–7V
Driveroutput 5to25V 2to6V 1.5to6V
Driverload <3k 100 60