Understanding Serial Communications

Background knowledge on RS-232, RS-422, RS-485, baud rates, and other serial communication concepts.

📄️ What is the difference between Full Termination, Half Termination and Biasing resistors?

A terminating resistor is simply a resistor placed at the ends of a cable. The value of the terminating resistor is ideally the same value as the characteristic impedance of the cable.

📄️ How Do I Efficiently Utilise Hardware Decoding on a BB-400 Using FFmpeg?

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📄️ How far will RS232 communicate?

RS232 will reliably communicate up to 15 metres (~50 feet). It may be the case that with a well shielded cable in a noiseless environment greater distances can be achieved.

📄️ How far will RS422/485 communicate?

RS422/485 can reliably communicate up to 1.2 kilometres (~4000 feet).

📄️ Is Serial tunnelling suitable for my application?

An introduction to Serial tunnelling; what is it and how can you use it?

📄️ RS232, RS422 & RS485 Standards

RS232 Standard

📄️ What is a FIFO?

A FIFO (First In First Out) is a type of buffer, where the first byte to arrive is the first to leave.

📄️ What is a UART?

Brainboxes UARTA UART (Universal Asynchronous Receiver Transmitter) was one of the first really successful integrated circuits. It makes PC serial communications possible and all of Brainboxes Serial Devices (and almost all Bluetooth devices) contain a UART. In order to transmit data along a single wire it must be converted from its native parallel format (inside the PC) into a stream of 1's and 0's, and vice versa on the receive side.

📄️ What is Autogating?

When the gating of transmitter and receiver lines are controlled through software (using RTS) in a multitasking operating system, it can sometimes take too long for a transmitter to become a receiver because the transmitter can not set RTS false quick enough. This means that when the transmitter finishes transmitting data it can potentially lose part of the response because it is unable to become a receiver in time.

📄️ What is DTR/DSR Flow Control?

DTR/DSR Flow Control is a flow control method that is part of the RS232 standard. It uses two pins on the RS232 connector, DTR (Data Terminal Ready) and DSR (Data Set Ready). These two control lines allow the receiver and the transmitter to signal each other about their readiness to communicate.

📄️ What is RTS / CTS Hardware Flow Control? A Simple, Must-Know Guide

RTS / CTS Flow Control

📄️ What is the difference between RS422 communication and RS485 communication?

RS422 Standard

📄️ What is the purpose of the buffer on a UART?

In the early days of serial communications buffered UARTS were not really necessary. This is because all operating systems were not multi-tasking, I.e. in DOS for example you did not edit text and communicate simultaneously.

📄️ What is Xon / Xoff Software Flow Control?

Xon / Xoff is a software flow control mechanism.