RS-485 is a bi-directional, half-duplex communication protocol that allows multiple drivers and receivers to be attached to the bus, with each driver capable of detaching from the bus. This specification meets all RS-422 requirements and is more robust than RS-422. Features higher receiver input impedance and wider common-mode range (-7V to +12V).
RS-232 is a communications standard initially developed for modulators, printers, and other PC peripherals, offering single-ended baud rates of 20kbps and later speeds to 1Mbps. Additional specifications for RS-232 include: nominal ±5V transmit level, ±3V receive level (spacing/symbol), 2V common-mode gain, 2200pF maximum cable load capacitance, 300Ω maximum driver resistance output, 3kΩ maximum receiver ( load) impedance, 100 ft (typ) maximum cable length. RS-232 is only used in point-to-point communication systems and cannot be used in multi-point communication systems. All RS-232 systems must abide by these restrictions.
RS-422 is a one-way, full-duplex communication protocol suitable for messy industrial environments. The RS-422 specification allows a single driver to communicate with multiple receivers, and data signals are transmitted differentially at a rate of up to 50Mbps. The receiver common-mode range is ±7V, the driver output resistance is 100Ω, and the receiver input impedance can be as low as 4kΩ.
RS-232: Used for communication with modems, printers, and other PC peripherals. The maximum cable length is 100 feet (typical).
RS-422: Suitable for single host (driver) industrial environment. Typical applications include: process automation (chemical industry, brewing, papermaking), factory automation (automobile manufacturing, metal processing), HVAC, security, motor control, motion control, etc.
RS-485: Suitable for multi-host/driver industrial environment. Its typical applications are similar to RS-422, including: process automation (chemical industry, brewing, papermaking), factory automation (automobile manufacturing, metal processing), HVAC, security, motor control, motion control.
RS-485 optical fiber transceiver supports data (TXD or SD) transmission control, which improves the ability to adapt to various software and simplifies the control method. Optical fiber MODEM supports a variety of optical fiber connection methods between asynchronous serial ports. It supports Two devices with asynchronous serial ports perform full-duplex or half-duplex communication through optical fibers. The communication distance can reach up to 4 kilometers for multi-mode and 20 kilometers for single-mode. The transmission rate of RS-232 signals is up to 115.2Kbps, RS- The signal transmission rate of 485 can reach up to 460Kbps, and the interfaces of different electrical standards can be mixed. RS-232 equipment can be used to connect RS-485 equipment, which can replace RS-232 to RS-485 interface converter or photoelectric isolator , and provides excellent EMI/RFT (electromagnetic interference/functional test) characteristics.
