Communication and interfacing information

These pages contain general information about computer interfacing. Current standards are discussed and specifications and protocol definitions are present.

Serial RS232

A lot of background information about one of the oldest communication methods in computer world. Already developed in the early sixties it still remains an important computer interface because of its robustness and easy implementation on all kinds of equipment.

Serial RS485

Despite many modern network technologies available today, the old serial standard RS485 plays an important role in data acquisition and control applications in scientific and technical environments. The main advantage of the interface is that it is simple, allows long distances and high bit rates and can be operated from small controllers and intelligent sensors. The RS485 standard has been adopted by communication protocols as MODBus, Interbus-S and Profibus as the definition of the electrical layer of these protocols.

USB, universal serial bus

USB is the new standard in PC to device communication. The goal was to replace both the serial RS232 and parallel interfaces with a new bus architecture which would be plug-and-play compatible.

On-line CRC calculation

The on-line CRC calculation form can be used to calculate for every input string the CRC16, CRC-CCITT and CRC32 values. There is an explanation of the way this algorithm works and free routines are available for download.

ASCII character set

The ASCII character set is the de facto standard for coding text documents. Although extend character sets have been defined like the ISO sets and UTF-8, these still use the same coding as once defined in the American Standard Code for Information Interchange.