Everything You Need To Know About RS485

Name: Everything You Need To Know About RS485
Rating: 4.6 (606 reviews)

Learn how to Build, Maintain and Troubleshoot RS485 communication networks

Created byEmile Ackbarali

Last updated 5/2026

English

What you'll learn

Be aware of the two areas of consideration for RS485 communications
Understanding of communication port parameters
Understanding of cabling standards
Configure RS485 communications between a PLC and a Computer
Be able to effective use a USB-to-RS485 converter for connection to a Computer
Understand the process of serial data transmission
Be able to troubleshoot any RS485 based network in the field of plant automation

Course content

6 sections • 41 lectures • 1h 52m total length

Introduction & Course Guide3:20
Accessing Attached Resources and Setting Optimal Video Resolution2:23

The Four Communication Port Parameters1:29
The four parameters are baud rate, number of data bits, number of stop bits and also parity. In addition to that, two very important rules of RS485 communications are stated.
Synchronous Serial Transmission3:40
In order to get a firm grasp of the four communication port parameters, you have to understand how data is transmitted along wires. Specifically, you have to understand a particular type of transmission know as synchronous serial transmission.
Asynchronous Serial Transmission1:56
In asynchronous serial transmission, the clock signal is removed and the synchronization of bit rate is done through software settings.
Baud Rate2:14
The bits per second rate is known as the baud rate when talking about serial transmission.
The Serial Data Frame3:58
Each byte of data that is sent is framed by synchronization and error checking bits. Together with the data that is sent, the data stream is known as a data frame.
Data Bits1:27
The number of data bits communication port parameter in RS485 allows the selection of either 7 or 8 bits. Many times, however, this selection is not given and the parameter is defaulted to 8 bits.
Start and Stop Bits1:43
The start and stop bits mark the start and end of a serial data frame and is used by the receiver as such.
Parity3:35
Parity is expressed by a single bit. It is a form of error checking. There can be even, odd or no parity.
An Example Real World Serial Data Stream3:55
We look at how two ASCII characters "OK" are transmitted serially.

What we are going to do in this Section1:45
A brief step by step description of the content that will be covered in the section.
An Overview of the Direct Logic DL05 PLC2:08
A look at the different physical characteristics of the Direct Logic 05 PLC.
The Physical Hardware Setup1:50
I show you how the hardware is connected on my workbench.
Configuration of the DL09 PLC Port #2 Parameters3:00
Using the PLC configuration software, the communication port parameters for Port #2 on the PLC is configured.
Introduction to Terminal Applications2:05
A brief description of a terminal application and what it does.
Downloading and Installing the Terminal Application1:23
The terminal application will receive data from the PLC via the virtual serial port on the laptop. This lecture shows how to download and install the application.
Programming the PLC to send Serial Data2:39
The PLC is programmed to periodically send serial data to the laptop via the serial connection. It will be programmed to send the phrase "Hello World!".
Viewing the Serial Data from the PLC2:45
The terminal application is used to view the serial data coming through the virtual serial port of the laptop from the PLC.
The Effect of Mismatched Baud Rate3:01
The baud rates are set up to be different between the PLC and the laptop. The effect of this is viewed via the terminal application.
The Effect of Mismatched Stop Bits, Data Bits and Parity2:43
One parameter at a time, the stop bits, data bits and parity are setup to be mismatched and the effect is seen via the terminal application.

What we are going to do in this Section2:37
A brief step by step description of the content that will be covered in the section.
A look at the actual USB-to-RS485 Converter that will be used.1:26
The actual USB-to-RS485 converter is shown and the functions of each part is explained.
A look at the actual MT-102 Remote Terminal Unit that will be used.1:31
The actual physical MT-102 remote terminal unit is shown.
A Schematic of the Computer to RTU Connection2:44
Via a schematic, the details of the connection of the computer to the RTU via the USB-to-RS485 converter is shown.
A look at the actual Computer to RTU Connection on the Workbench1:19
The actual physical connection between the Laptop and the MT-102 RTU is shown on the workbench.
Configuration of the Communication Port Parameters on the MT-102 RTU2:28
The MT-102 is configured using it's programming/configuration software. Specifically, it is set up for communication via RS485. Modbus communication is also activated on the RS485 port.
Identification of Modbus Unit ID and relevant Memory Blocks1:27
For the Modbus communication to be understood, details are given on the Modbus Unit ID as well as some relevant memory blocks that will be read.
RS485 Communication using Modscan322:10
Modscan32 is set up to read memory blocks from the MT-102 RTU to show that the RS485 communication is operating as desired.
Effect of Mismatched Port Parameters on Communication2:28
The Modscan32 port parameters are changed to simulate mismatched port settings, and the effect is shown.
Effect of Interchanged Signal Wires on Communication2:17
The RS485 signal wires are interchanged to simulate a hardware connection issue and the effect on the communication is shown.

RS485 Interconnection - Daisy Chain3:00
RS485 devices are typically connected in a pattern known as Daisy Chain.
Full Duplex vs. Half Duplex3:27
A comparison is made between full duplex (RS232) and half duplex (RS485) transmission.
Single-Ended vs. Differential Data Transmission2:54
A comparison is made between Single-Ended (RS232) and Differential (RS485) data transmission systems.
RS485 Device Receiver and Transmitter Components3:25
Each RS485 device has a receiver and a transmitter.
RS485 Voltages for Binary Representation3:48
A look at the voltages that are used by transmitters and receivers to transport binary data.
Understanding Tri-State2:31
A look at how an output can be in one of 3 states. Binary 1, Binary 0 or high impedance ... and why this is necessary.
The Significance of Signal-to-Noise Ratio7:36
Signal to Noise on a communication line is described from a very practical standpoint and the significance of it in the design of serial communications systems is emphasized.
Unshielded and Shielded Twisted Pair Cabling (UTP/STP)3:24
UTP cabling is used for most RS485 cabling installations. STP will be used in areas of very high EMI.
Twisted Pair Noise Rejection6:45
How the act of twisting wires together rejects noise.

Requirements

Fundamentals of binary data systems and how computers store and exchange binary data

Description

RS-485 is the de facto workhorse of data communications in the field of plant automation.

It is very effective in applications with significant electrical interference (noise) requiring a long transmission distance. Thus, the standard is often used in industrial applications. It is as an inexpensive local area network (LAN) connection that allows multiple receivers to connect within a multi drop configuration. RS-485 does not include a communications protocol.

This course delivers the theoretical and practical aspects of RS-485 in a very effective way, so that at the end, you will be able to build, maintain and troubleshoot any RS-485 based network in the plan automation field. The course features a live physical connection between a PLC and a Computer via a USB-to-RS485 converter, an example that is key to effective troubleshooting of RS-485 systems.

After completing this course, you will be able to integrate devices from the same manufacturers and different manufacturers, that are RS-485 compliant, to form a complete seamless network.

Who this course is for:

Electrical Engineers
Electrical Technicians
Electrical Tech or Engineering Students
Process Control Technicians

Everything You Need To Know About RS485

What you'll learn

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Course content

Introduction2 lectures • 6min

Communication Port Parameters9 lectures • 24min

Communication Port Parameters in Practice10 lectures • 23min

Live RS485 Communication to a Remote Terminal Unit device10 lectures • 20min

RS485 Signalling and Cabling9 lectures • 37min

Bonus Section - How to Always get the Lowest Prices for my Courses1 lecture • 2min

Requirements

Description

Who this course is for: