Serial data converters are used to interconnect two different serial standards, such as RS232 to RS422, USB to RS232, etc.  Interfaces, features, and environmental parameters are important specifications to consider when searching for serial data converters.

Input and Output Standards

Serial data converters can have one of several input and output standards that they connect between.  These include RS232, RS422, RS485, current loop, fiber optic and USB.  RS232 stands for Recommended Standard 232C.  A standard interface approved by the Electronic Industries Association (EIA) for connecting serial devices. RS232 is a serial communication standard providing asynchronous communication capabilities with hardware flow control, software flow control, and parity check. It is widely used.  Almost all gears, instruments with digital control interface or communication devices are equipped with RS232 interface. The typical transmission speed of RS232 is 9600bps at 15 meters. RS422 supports multipoint connections whereas RS423 supports only point-to-point connections. RS422 provides much longer transmission distance but less signal line compared to RS232. RS422 adopts a differential transmission technology and provides high-speed transmission up to 10Mbps and maximum transmission distance up to 1.2km at 110kbps. RS485 is almost identical to RS232 except that transmissions are three-way rather than two-way.  RS485 is often used in applications where a single controller needs to control multiple devices.  Up to 64 devices may be connected under RS485. RS485 is an enhanced version of RS422. It is compatible to RS422 interface and provides 2-wire bus topology. By using RS485 2-wire bus, you may establish a very inexpensive network system. However, RS485 only defines electronic signal specifications, users must define software protocol for 2 wire communication by themselves.  A current loop interface is a transmission technique that recognizes current flows, rather than voltage levels.  Fiber optic is a transmission medium designed to transmit digital signals in the form of pulses of light. Universal Serial Bus (USB) is the standard serial bus for low-to-medium speed peripheral device connections to personal computers, including keyboards, mice, modems, printers, joysticks, audio functions, monitor controls, etc.  The data rate for serial data converters is rate (in bits/sec) at which serial data is transferred.  Isolating voltage is the maximum voltage that the device can isolate at each port.

Features

Common features for serial data converters include indicators and agency approvals.  Indicators include lights, or other types of indicators to signal features such as power-on, transmission, collisions, etc.  Common agency approvals include FCC, CSA Mark (US, C and US, NRTL/C), C-UL US Listing Mark, TÜV Rheinland (US, C, US & C), and UL Listing Mark.  Important environmental parameters to consider include operating temperature and operating humidity.