Serial and Protocol Converters: RS-232, RS-485, CAN

Which serial standard does your device speak?

Serial devices are not all electrically the same. RS-232 is a short point-to-point link, usually on a DB9 connector. RS-422 and RS-485 use differential pairs that carry data much farther and resist noise, and RS-485 lets many devices share one two-wire bus. Read the device manual before choosing, and match the converter's standard, the connector gender and the pin layout; some units connect to a screw terminal block instead of a DB9. A converter that lists all three standards usually switches between them with a jumper or a setting.

Where serial links usually go wrong

Most failed serial links come down to wiring or setup, not hardware. Check that baud rate, parity and stop bits match on both ends, and that the cable is straight or null-modem as the device expects. Isolated converters add a barrier that protects the computer from ground loops and surges, which matters in industrial settings. USB converters also depend on a chip driver, so check support for your operating system. On long RS-485 or CAN runs, a termination resistor at each end keeps the signal clean.

Questions about Serial and Protocol Converters: RS-232, RS-485, CAN

What is the difference between RS-232 and RS-485?

RS-232 links two devices over a short cable with single-ended signals. RS-485 uses a differential pair, runs over much longer distances, tolerates electrical noise and lets many devices share a bus. They are not directly compatible, so a converter is needed to join them.

Do I need an isolated converter?

Choose isolation when devices sit on different grounds, in noisy industrial settings, or when connected equipment could put surges onto your computer. For simple bench use with a small device, a non-isolated adapter is usually enough.

Can I use a USB to RS-232 adapter with an older serial instrument?

Often yes, but check the instrument's voltage levels, flow control needs and connector type. Some older instruments need hardware flow control lines, which some adapters leave unconnected, so look for a full set of signal lines in the listing.