Serial standards rs 232 communications is the most popular method of plc to external device communications.
Serial communication cable types.
Rs 232 is a communication interface included under scada applications.
The cables that carry digital video are almost invariably serial such as coax cable plugged into a hd sdi port a webcam plugged into a usb port or firewire port ethernet cable connecting an ip camera to a power over ethernet port fpd link etc.
There are 2 types of rs 232 devices.
The form of connectors depends on the particular serial port used.
Most universal serial bus usb cables connect a computer with a peripheral device such as a keyboard or mouse rather than to another computer.
Other standards such as rs422 and rs423 are similar to rs232 although they permit higher transmission rates and longer cable distances.
Often used for intercoms speakers and security systems this cable is designated as cm and cl2 or cmg so the insulation is flame resistant and approved for in wall installation in single level facilities.
According serial data cables for these systems require the additional lines to be incorporated into the serial data cables for them to operate correctly.
Dte data terminal equipment and a common example is a computer.
They are null modem and straight cable.
However special network adapters sometimes called dongles connect an ethernet cable to a usb port indirectly.
Rs 232c rs 422a rs 485 are eia electronic industries association communication standards of these communication standards rs 232c has been widely adopted in a variety of applications and it is even standard equipment on computers and is often used to connect modems and mice sensors and actuators also contain these interfaces many of which can be controlled via serial communication.
Typical rs232 serial data cable.
The transmission modes are classified as simplex half duplex and full duplex.
There will be a source also known as a sender and destination also called a receiver for each transmission mode.
Types of serial cables.
Types of cables used in control communication control cables.
This serial communication standard is widely used and is often equipped on computers as standard.
In null modem cable the tx transmitter pin of the male connector is linked up with the rx receiver pin of the female and the rx pin of the male is connected to tx pin of the female.
The rs232 cable shown above gives the more likely connections seen in an rs232 cable.
Usb cables feature twisted pair wiring.
Serial cables are typically used for rs 232 communication.
It has an uninsulated ground wire is not counted in the number of wires.
Control cables are used to connect instrument transformers coils of circuit breakers and contactors control switches meters protection devices and other control and monitoring equipment.
Serial communication can take many forms depending on the type of transmission mode and data transfer.
Shielded cable has a layer of foil that blocks signal interference from nearby equipment and devices.
A suitable cable is shown below.
