RS-232, also known as Recommended Standard 232, is one of the oldest and best-known standards for serial data transmission. In industrial settings, it is often associated with the designation V.24, whereby V.24 describes the signal and function assignments, and the electrical levels are additionally defined by V.28 or RS-232.
Technical Specifications
With RS-232, all signals are referenced to a common ground, which is why it is an unbalanced interface. Data is transmitted serially and asynchronously, that is, bit by bit without a separate clock line. Typically, negative voltages represent a logical 1 and positive voltages represent a logical 0; valid levels usually lie outside the range of −3 to +3 volts.
Typical Levels
In practical applications, RS-232 operates at comparatively high signal levels compared to TTL or CMOS interfaces. Valid states are often specified as ranges from approximately -3 to -15 volts for a logical 1 and +3 to +15 volts for a logical 0; levels between −3 and +3 volts are considered undefined.
Practical Experience in Measurement Technology and at Delphin
In measurement technology, RS-232 is primarily used for serial communication with measuring instruments, sensors, display devices, or older automation components. Serial interfaces such as RS-232 also play a role at Delphin in integrating measurement and data acquisition systems into existing infrastructures, service laptops, or external devices, thereby enabling data exchange or configuration.