Automation industry is a widely developing one these days. The demand for various input-output modules also spiking up day by day. Automation engineering deals with thousands of standard protocols and codes. One such regularly heard protocol is RS-232. Before getting to the details, a basic idea of some telecommunication terms is necessary.
DTE and DCE devices
Telecommunication network is a collection of Data Terminal Equipment (DTE) and Data Communication Equipment (DCE). DTE is basically the data or signal source and DCE acts as the interface medium for the transmission of signals from DTE. Computers and routers come under the category of DTE devices and modem is an example of a DCE device.
What is the role of RS-232 in automation industry?
The sequential transmission of binary pulses via a communication channel is termed as serial communication. Recommended Standard 232 or RS-232 is a standard serial communication protocol used for the binary data transmission between connected DCE and DTE devices in a telecommunication network. DB 25 and DB 9 connectors are used for the data transmission employing RS-232 protocol.
DB 9 Connector
Features of RS-232
RS-232 is very common and inexpensive. Programmable Logic Control (PLC) uses RS-232 protocol for data communication between various DTE and DCE devices such as HMI, motor controllers, drives, display system etc. The only thing is that each connected device should be able to use this standard protocol. Even two PLCs can communicate each other with the help of this RS-232 protocol.
Drawbacks
- The speed of data transmission between the devices is comparatively very less for this protocol. It transmits at a speed of 20 kilobytes per second.
- Two inter communicating devices employing RS-232 protocol should be within a distance of 50 feet. Once the distance between devices increases above 50 feets, the voltage drops and also ends up with data transmission losses.
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