Industrial Control Panels In Depth Look Part 5: Communication

Industrial Control Panel Basics:    • Industrial Control Panel Basics  

In todays video we are going to be taking another look at industrial control panels. More specifically, we are going to be looking the at the parts of the panel that allow for communication, both within the panel itself, and to other locations. For more information about the basics of industrial control panels, please reference our other video, which we will link to in the description below.

One important function of industrial control panels, is to gather data from various instruments or devices specific to the use case for that control panel. But what happens with this data? In many cases the data is used by the PLC itself which receives signals from the instruments. The PLC uses this data to process commands based on its internal programming. There are other important uses, however, where data needs to be able to be transferred to or from the PLC from other non-instrument devices.

Let’s first talk about the network switch. A switch is a device that allows any piece of hardware that is connected to it, to send and receive data to and from the other devices on that switch. The switch acts as a broker that decides how to route messages from one device to another. When a device plugged into a switch tries to reach another device, the switch decides which cable the message should be sent on. For more detailed information on switches, see our video “Basics of Switches, Routers and Hubs”. In most scenarios there are multiple devices that need to be able to communicate with each other over an ethernet network. Some of the most common examples are the PLC and HMI. The HMI may be centrally located somewhere or a touch screen within the panel (also sometimes referred to as OIT or operator interface terminal). The PLC may also need to communicate with an ethernet radio, VFD’s, power monitoring devices, smart instruments, or other specialty devices that allow communication over an ethernet network. Again, the network switch acts as a broker to facilitate communication between any of these devices and allows multiple devices to communicate with each other while only requiring one cable to the device itself.

The other device that we want to highlight today used for communication is the industrial communication radio. Industrial radios are certainly not used in all control panels but they are used often. Industrial radios are often used when communication over long distances is required which is one reason why most SCADA systems utilize these heavily. Examples of use would be to monitor data from multiple locations within a city where all data is aggregated back to a central control room. Another example may be the monitoring of widely dispersed sites in an oil field. The radio allows communication over long distances without communication cables that can be costly, or impossible to install. Depending on the type of radio that is being used in the panel and the communications protocol it is using, it may be connected directly to the PLC, or through the network switch.

Keep in mind the that in order to communicate the radio also needs an antenna, usually mounted somewhere on the building in which the control panel is installed or possibly on a conduit in cases where the panel is out doors. The type of antenna that is used will vary with the radio frequency, the geography of the area and the location of other radios within the network. The two most common types of antenna are either Yagi and Omni antennas. For more information about industrial antennas, please see our other video, where we go over these in great detail.

Additional Links -

Website:
https://rspsupply.com/
Engineering Page:
https://rspsupply.com/engineering/
Panel Fabrication Page:
https://rspsupply.com/panel-fabrication/
Procurement Services Page:
https://rspsupply.com/procurement-ser...
Manufacturers Page:
https://rspsupply.com/manufacturers.aspx
Networking & Communication:
https://rspsupply.com/c-6263-networki...
Antennas:
https://rspsupply.com/c-1577-antennas...
PLCs & IO:
https://rspsupply.com/c-3872-plcs-io....
Connectors:
https://rspsupply.com/c-7172-connecto...
Sensors:
https://rspsupply.com/c-10189-sensors...