the maximum length of a standard rs-232 cable is 25.
the maximum length of a standard rs-232 cable is 25.
what is the maximum length of a standard rs-232 cable?
25
in the book "pc 97 hardware design guide", microsoft deprecated support for the rs-232 compatible serial port of the original ibm pc design. today, rs-232 has mostly been replaced in personal computers by usb for local communications. advantages compared to rs-232 are that usb is faster, uses lower voltages, and has connectors that are simpler to connect and use. disadvantages of usb compared to rs-232 are that usb is far less immune to electromagnetic interference (emi) and that maximum cable length is much shorter (15 meters for rs-232 v.s. 3 - 5 meters for usb depending on usb speed used).
rs-232
null modem









































null modem is a communication method to directly connect two dtes (computer, terminal, printer, etc.) using an rs-232 serial cable. the name stems from the historical use of rs-232 cables to connect two teleprinter devices or two modems in order to communicate with one another; "null modem" communication refers to using a crossed-over rs-232 cable to connect the teleprinters directly to one another without the modems. 









































it is also used to serially connect a computer to a printer, since both are dte, and is known as a "printer cable".
null modem