RS-423

RS-423 is a technical standard promulgated by the Electronic Industries Alliance (EIA) specifying the physical interface for serial data communication. It is a serial communication standard primarily used for connecting data terminal equipment (DTE) to data circuit-terminating equipment (DCE). It is functionally similar to RS-232 but uses balanced, or differential, signaling to improve noise immunity and permit greater distances.

RS-423 is typically used for lower data rates than its faster counterpart, RS-422. Although the physical connector is often a DB-25, this is not a requirement and other connector types can be used. A single RS-423 transmitter can connect to a single RS-423 receiver. This is a single-ended configuration, meaning only one driver and one receiver are present in the communication link.

Key characteristics of RS-423 include:

• Single-Ended Signaling: Employs a single-ended driver and receiver, unlike RS-422's differential signaling on both ends. This makes it less robust in noisy environments compared to RS-422.
• Distance: Supports communication distances up to 1200 meters (4000 feet) at lower data rates. Maximum distance decreases as the data rate increases.
• Data Rate: Maximum data rate is specified as 100 kbps.
• Voltage Levels: Uses a signal level of ± (4-6) V.
• Impedance: Designed for a 150-ohm load impedance.

RS-423 is often implemented using the same connectors as RS-232, such as the DB-25 or DB-9, but the pin assignments and electrical characteristics are significantly different. This can lead to confusion, as a physically compatible connection may not function correctly due to the electrical incompatibility between the two standards. While once commonly used, RS-423 has largely been superseded by RS-422 and RS-485 in modern applications due to their improved noise immunity and multi-drop capabilities.