== Voltages ==

== Voltages ==

RS232 specification says that the voltages may be ±25V, however ±5 V, ±10 V, ±12 V, and ±15 V are all common.

RS232 specification says that the voltages may be -7V - +12V.

A 1 is represented as -3V to -25V

A 1 is represented as Positive Voltages (B-A > +200 mV)