Rs232 serial multiplexer

After the data is transmitted, the transmitter sends the stop bits. It can be either 1 bit or 1. The following image shows the frame format of the RS protocol. Though RS is considered to be a complete standard, many manufacturers may not abide by the standards. Some manufacturers may implement the complete specifications and some implement just a partial specification.

The reason behind this variation in implementation of the RS standard is that not all devices and applications require the full specifications and functionality of the RS Protocol.

For example, a serial Modem using RS may require more control lines than a serial Mouse using serial port. Then how does the Transmitter and Receiver, which might use different set of specifications, successfully transmit or receive the data? A process called Handshaking is used for this purpose.

Handshaking is a process of dynamically setting the parameters of a communication between the transmitter and receiver before the communication begins. The need for handshaking is dictated by the speed at with the transmitter DTE transmits the data, the speed at which the receiver DCE receives the data and the rate at which the data is transmitted.

In an asynchronous data transmission system, there can be no handshaking, hardware handshaking and software handshaking. If handshaking is not used, then the receiver DCE must read the data that is already received by it before the transmitter DTE sends the next data.

For this, the receiver uses a special memory location called Buffer and since it is used at receiver end, it is called Receiver Buffer. The received data is stored in the buffer before it is read by the receiver. The Receiver Buffer can typically store a single bit of data and this data must be cleared read before the next data arrives and if it is not cleared, the existing data will be overwritten with the new data.

The following image shows a typical transmission and reception of data using transmitter and receiver buffers. In this setup, the receiver has successfully read the first three bits of data but did not read the fourth bit.

Hence, the next bit i. To avoid situations like this, we need some sort of Handshaking mechanism either Software or Hardware Handshaking. In Hardware Handshaking, the transmitter first asks the receiver whether it is ready to receive the data. The receiver then checks its buffer and if the buffer is empty, it will then tell the transmitter that it is ready to receive. The transmitter will transmit the data and it is loaded into the receiver buffer.

During this time, the receiver tells the transmitter not to send any further data until the data in the buffer has been read by the receiver. The RS Protocol defines four signals for the purpose of Handshaking:. With the help of Hardware Handshaking, the data from the transmitter is never lost or overwritten in the receiver buffer. When the receiver is ready, it pulls the CTS line to high.

The transmitter then transmits the data. Additionally, there are two other wires used in Handshaking. Often, these two signals are used in modem communication.

Thanks for your help. Regards Paul. Super Member. HI, Thank for the reply. Problem solved. Yes it certainly will. It seems that this is perfect.

And I actually have one. Thank you. Latest Posts. A little insight with writing relocatable code please. You need two computer to do it. But if you only He said, this is a simple IR receiver circuit which plugs into Data Acquisition. Electronic Kits. Electronic Schematic. Ham Radio.

Power Supply.