RS232 obtains the voltage for the path used for the dataexchange between the devices. It is defined as the connection between the DTE (Data Transmission Equipment) and DCE (Data Communication Equipment) devices. It is used in serialcommunication up to 50 feet with the rate of 1.
492kbps. Rs232 supply voltagesup to +15V. Universal Asynchronous DataReceiver & Transmitter (UART)used in connection with RS232 for transferring data between printer andcomputer. The micro controllers are not able to handle such kind of voltagelevels, so the micro controllers and connectors are connected between RS232signals.
These connectors known as the DB-9Connector as serial port and these are of two types i.e., Male connector (DTE) & Female connector (DCE). ELECTRICALSPECIFICATIONSNow, after collecting knowledge about RS232, let usdiscuss about the electrical specifications. Here are some specifications, i.e.,· Voltagelevels: Rs232 also used as ground & 5 V level. Binary 0works with voltages up to +5V to +15Vdc.
It is called as ‘ON’ or spacing (high voltage level) whereas Binary 1 workswith voltages up to -5V to -15Vdc. It is called as ‘OFF’ or marking (lowvoltage level).· Receivedsignal voltage level: Binary 0 works on the receivedsignal voltages up to +3V to +13 V dc & Binary 1 works with voltages up to-3V to -13 V dc.· LineImpedances: The impedance of wires is up to 3 ohmsto 7 ohms & the maximum cable length are 15 meters, but new maximum lengthin terms of capacitance per unit length.· OperationVoltage: The operation voltage will be 250 V AC max.· CurrentRating: The current rating will be 3 Amps max.· Dielectricwithstanding voltage: 1000 VAC min. · SlewRate: The rate of change of signal levels is termed asSlew Rate.
With its slew rate is up to 30 V/microsecond and the maximum bitrate will be 20 kbps. Theratings and specification changes with the change equipment model. HowRS232 Works?RS232 works on the two way communication that exchangesdata to one another.
There are two devices connected to each other, (DTE) Data Transmission Equipment &(DCE) Data Communication Equipment which has the pins like TXD, RXD, RTS & CTS. The TXD is fortransmission, Rxd is for receiving data, RTS is to request to send & CTS isto clear to send. Now, from DTEsource, the RTS generates therequest to send the data so from the other side DCE source, the CTSclears the path for receiving the data. After clearing path, it will givesignal to RTS of the DTE source to send the signal.
The bitstransmitted from DTE to DCE. Now again from DCE source, the request can begenerated by RTS and CTS of DTE sources clears the path for receiving the data and gives asignal to send the data. This is the whole process through which data transmissiontakes place.Forexample: The signals set to logic 1, i.e., -12V.
The datatransmission starts from next bit and to inform this DTE sends start bit toDCE. The start bit is always ‘0’, i.e., +12 V & next 5 to 9 characters isdata bits. If we use parity bit, then 8 bits are being transmitted whereas ifparity doesn’t use, then 9 bits are being transmitted.
The stop bits send bytransmitter whose values are1, 1.5 or 2 bits long after the data transmission.