Keep in mind that a high RS-232 voltage level actually represents a logic 0, and that a low RS-232 voltage level refers to a logic 1. Transmitted Data (TD): One of two separate data signals, this signal is generated by the DTE and received by the DCE.

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, and RTS& CTS. Now, from DTE source, the RTS generates the request to send the data.

This allows up to 32 devices on a single network without repeaters. The devices can also be connected up to 4000 feet away from the PC. The disadvantage is that each device must have its own unique address.

To check whether or not an RS-232 serial port is working, perform an RS-232 loopback test by doing the following:

1. If your serial port is not female, convert it by taking a female/female cable or gender changer and plugging it into the serial port.
2. Take a metal paperclip or wire and cross pins 2 and 3.

You can check what device is using what COM port from the Device Manager. It will be listed under the hidden devices. From the Device Manager, select View – Show Hidden Devices. Now when you expand the (PORTS) COM ports section you will see all of the COM ports listed there.

RS-232 (or Recommended Standard 232) is a standard computer communications system that’s more commonly known as a serial connection. You’ve probably used an RS-232 connector if you’ve ever connected a modem to an older PC (whether or not you knew what it was called).

It output is digital but, not as TTL or CMOS standard. It s output signal varies between +10 to -10 voltage. Recommended standard 232 ic is used only for serial communication which is digital in nature.

RS232 is full-duplex, RS485 is half-duplex, and RS422 is full-duplex. RS485 and RS232 are only the physical protocol of communication (ie interface standard), RS485 is the differential transmission mode, RS232 is the single-ended transmission mode, but the communication program does not have much difference.

Maximum cable lengths Cable length is one of the most discussed items in RS232 world. The standard has a clear answer, the maximum cable length is 50 feet, or the cable length equal to a capacitance of 2500 pF.

The guidelines established by paragraph 3.1 of the RS-232-C standard recommend limiting the cable length to 50 feet or less. The standard does allow the cable length to exceed 50 feet, provided that its total capacitance is less than 2500 pF. No specific cable construction type is recommended in the EIA specification.

50 feet

Basically, RS232 can transfer a single byte of data over a serial cable having between 3 to 22 signals and running at speeds from 100 to 20k baud. Common baud rates used are 2.4k, 9.6k, 19.2k; the cable length can be up to 50ft.

In the serial port context, “9600 baud” means that the serial port is capable of transferring a maximum of 9600 bits per second. The higher the baud rate, the more sensitive the cable becomes to the quality of installation, due to how much of the wire is untwisted around each device.

The higher a baud rate goes, the faster data is sent/received, but there are limits to how fast data can be transferred. You usually won’t see speeds exceeding 115200 – that’s fast for most microcontrollers.

How to calculate Baud Rate? Baud Rate refers to the number of signal or symbol changes that occur per second. It is denoted by ‘r’ is calculated using baud_rate = Bit rate/Number of bits. To calculate Baud Rate, you need Bit rate (R) and Number of bits (n).

Baud, or baud rate, is used to describe the maximum oscillation rate of an electronic signal. For example, if a signal changes (or could change) 1200 times in one second, it would be measured at 1200 baud. If a modem transfers a single bit per electronic pulse, one baud would be equal to one bit per second (bps).

The baud rate signifies the data rate in bits per second. The default baud rate in Arduino is 9600 bps (bits per second). We can specify other baud rates as well, such as 4800, 14400, 38400, 28800, etc.

Other “standard” baud are 1200, 2400, 4800, 19200, 38400, 57600, and 115200. The higher a baud rate goes, the faster data is sent/received, but there are limits to how fast data can be transferred. You usually won’t see speeds exceeding 115200 – that’s fast for most microcontrollers.

Bit rate is the transmission of number of bits per second. On the other hand, Baud rate is defined as the number of signal units per second. Bit rate is also defined as per second travel number of bits. Baud rate is also defined as per second number of changes in signal.

A member of our scientific collaboration designed a data acquisition box with with 4 channels @ 1 kHz that synchronizes time with GPS. He uses USB 2.0 to have the box communicate with a computer, and the COM serial interface with a baud rate of 115200 is used to transfer data to the computer in ASCII format.