Welcome to another informative video brought to you by RealPars.
Today you will learn about RS-485.
If you are familiar with RS-232,
then you may already know a little bit about it.
If not, check out our other video What is RS-232.
The link will be provided below.
Before we get started on today’s video, if you love our videos,
be sure to click the like button below,
then make sure to click subscribe and the little bell
to receive notifications of new RealPars videos.
This way you never miss another one!
Just like it’s older brother RS-232,
RS-485 is a form of serial communication.
Think of RS-485 as the younger, faster brother of RS-232.
What made it such an advancement over RS-232
was the fact that it could transmit not only a single device to device transmission,
but also a communications bus to connect multiple devices at once.
The configuration and specifications of RS-485
make it faster and extend the range of data transmission.
You aren’t limited to fifty feet of cable like with RS-232.
The maximum cable length for RS-485 is typically listed as 1200 meters or about 4000 feet.
Much like RS-232, RS-485 doesn’t have an actual standard connector.
Many times the old DB-9 connector is used.
In some applications, terminal strips were used in place of a connector.
This helped RS-485 become a widely used
and very versatile form of serial communication.
Another advantage over RS-232 that I mentioned earlier
is the number of connectable devices.
RS-485 can handle up to 32 connected devices.
RS-232 could only handle one.
This allowed users in manufacturing facilities
to connect larger applications and whole machines with one protocol.
Another plus for RS-485 is that it is less susceptible to noise issues.
Electric noise can cause all kinds of problems for electronics.
RS-232 referenced ground to decipher the data it was transmitting.
This allowed for electrical noise to cause interference.
RS-485 avoids this issue which also allows for shielding of the cables to prevent noise.
You may be wondering, what can I do with serial communications, especially RS-485.
One very common example in the automation world
is remote control of VFDs or Variable Frequency Drives.
Many people just call them motor drives.
A simple network of a PLC, VFD,
and an HMI allows remote control of motors in an industrial setting.
Let’s say you were monitoring a water pump filling a vessel.
You decide that the water is not filling fast enough to keep up with demand.
With your RS-485 network, you can remotely monitor
and control that pump from a control center.
This is possible since the HMI is connected to your PLC via RS-485.
The PLC is also connected to the VFD via RS-485.
The PLC is programmed to monitor the level of the water in the vessel.
It also allows manual flow control if needed.
All of this allows you to speed up the VFD
that controls the speed of that water pump.
Problem solved thanks to RS-485 communications.
Let's talk about what we now know about RS-485.
It is faster and much more versatile than the older RS-232.
Users can utilize a longer cable, up to 1200 meters or about 4000 feet.
The greatest feature of RS-485
is the fact that you can connect up to 32 devices on one system.
RS-232 could only handle one at a time.
There is no standard connector for the protocol.
Most manufacturers still utilize a DB-9 connector.
You can also still simply use a terminal strip.
This makes utilizing RS-485 simple.
All in all, RS-485 really allowed full automation possible
with its ability to connect so many devices at once.
I truly hope this video was helpful.
Please don’t forget to check back later for more RealPars videos!
Make sure that you head over to realpars.com.
To find even more training material for all of your PLC Programing needs.
We offer many videos to assist you in learning PLC Programing
and landing that job in a high-paying,
highly thought after field of automation and controls engineering.
Go to realpars.com and subscribe to our highly effective training series now!