RS232 obtains the voltage for the path used for the data
exchange 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 serial
communication up to 50 feet with the rate of 1.492kbps. Rs232 supply voltages
up to +15V. Universal Asynchronous Data
Receiver & Transmitter (UART)
used in connection with RS232 for transferring data between printer and
computer. The micro controllers are not able to handle such kind of voltage
levels, so the micro controllers and connectors are connected between RS232
signals. These connectors known as the DB-9
Connector as serial port and these are of two types i.e., Male connector (DTE) & Female connector (DCE).
Now, after collecting knowledge about RS232, let us
discuss about the electrical specifications. Here are some specifications, i.e.,
levels: Rs232 also used as ground & 5 V level. Binary 0
works with voltages up to +5V to +15Vdc.
It is called as ‘ON’ or spacing (high voltage level) whereas Binary 1 works
with voltages up to -5V to -15Vdc. It is called as ‘OFF’ or marking (low
signal voltage level: Binary 0 works on the received
signal voltages up to +3V to +13 V dc & Binary 1 works with voltages up to
-3V to -13 V dc.
Impedances: The impedance of wires is up to 3 ohms
to 7 ohms & the maximum cable length are 15 meters, but new maximum length
in terms of capacitance per unit length.
Voltage: The operation voltage will be 250 V AC max.
Rating: The current rating will be 3 Amps max.
withstanding voltage: 1000 VAC min.
Rate: The rate of change of signal levels is termed as
Slew Rate. With its slew rate is up to 30 V/microsecond and the maximum bit
rate will be 20 kbps.
ratings and specification changes with the change equipment model.
RS232 works on the two way communication that exchanges
data 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 for
transmission, Rxd is for receiving data, RTS is to request to send & CTS is
to clear to send. Now, from DTE
source, the RTS generates the
request to send the data so from the other side DCE source, the CTS
clears the path for receiving the data. After clearing path, it will give
signal to RTS of the DTE source to send the signal. The bits
transmitted from DTE to DCE. Now again from DCE source, the request can be
generated by RTS and CTS of DTE sources clears the path for receiving the data and gives a
signal to send the data. This is the whole process through which data transmission
example: The signals set to logic 1, i.e., -12V. The data
transmission starts from next bit and to inform this DTE sends start bit to
DCE. The start bit is always ‘0’, i.e., +12 V & next 5 to 9 characters is
data bits. If we use parity bit, then 8 bits are being transmitted whereas if
parity doesn’t use, then 9 bits are being transmitted. The stop bits send by
transmitter whose values are1, 1.5 or 2 bits long after the data transmission.