Difference between Industrial Network and IT Network
Industrial network has unique requirements based on two-way communications. To understand this, lets think about a possible application; a bottle-filling plant. Let’s assume Real Time Automation is creating a new microbrew beer. The filling operation will be run on an Industrial network.
The network works well because it uses “handshaking” to ensure message delivery. To illustrate this attribute let’s say our bottling device begins filling a bottle at the command of the controlling system. The system is also responsible for sending the “stop filling” command when the bottle is full. If the message is lost on the network the PLC is aware because it does not receive a delivery response from the filler, (part of the handshaking) so it knows to resend the command.
Industrial control networks are connected to physical equipment, failure of a system has a much more severe impact than that of commercial systems. The various effects of failure of an industrial network include damage to equipment, production loss, and environmental damage, loss of reputation and even loss of life.
In the IT networking setting, such a lost transmission is rarely important. If a webpage gets lost in transmission, the user simply presses “refresh.” In the production setting, though, we can’t wait for Automation system to spill on the floor before someone manually turns off the filler. The acknowledgement or feedback saves money and time.
Bottle filling unit with Controller System
In an Industrial network, we also incorporate collision detection. If two messages collide in our network, the controlling PLC can resend the message to the device until it receives a delivery notice for the device. These transactions occur over just a few milliseconds. The magnificent operation must run at peak efficiency, an IT network would not accomplish this goal. That is because there is no collision detection. Another area of concern regards the specific needs of your plant operations. Take, for instance, the cost of downtime. When a network goes down in your Office setting, it is an inconvenience. Some work may be impossible. Often, an employee will simply need to move on to another task and tackle it without using the internet. Or perhaps switch to a 3G or 4G mobile device and send out an important email.
In a production setting, that downtime can be more costly. Assembly lines operating with continual processes can be rendered nonfunctional if one aspect fails. Critical processes could be ruined, leading to lost material, and money.
Think for a minute of a factory producing tempered glass for windows. A continues flow of glass moves from pour, to cut, over an assembly line, a mile long. Going through specific heat up, cool-down and rest cycles to properly temper it to defined specifications. If the line seized, you would be left with a mile of scrap glass. Much of it that would have to remove manually due to the fact it had cooled hard on a portion of the line that was meant to deal with hot malleable glass.
When designing an Industrial Ethernet network, you must consider options that make your network reliable. That often leads to increased costs. Environmental concern is another factor which plays important role in differentiating between the industrial and commercial or IT network. Heat and cold are two factors that can have a major effect on a network. Cold is particularly damaging. At relatively cold levels, near freezing, a cable is susceptible to impact, which can cause a break in the cable, destruction of the protective jacket, or attenuation. At even colder temperatures, the cable may become brittle and break through no large force, but instead through simple bending.
Heat is also damaging. The protective jacket may melt, leading to shorts and vulnerability. Heat also causes attenuation over time. Cables may not become physically susceptible when exposed to heat, but they can be made just as ineffective over time. The Industrial environment is harsh, and Commercial applications were not created for such environments. Taking measures to physically protect cables and connectors can minimize, or even negate, the effects of an industrial environment.
Commercial or IT network is almost always configured in a star topology. Industrial network has many different topology options to fit diverse industrial applications. The topologies include star, tree, line, and ring topologies. Another notable difference relates to use. Office network components are designed for a base level of use. Industrial network components can be considered for multiple levels of use and environmental abuse.
Industrial networks generally have a much deeper architecture than commercial networks.
Whereas the commercial network of a company may consist of branch or office Local Area Networks (LANs) connected by a backbone network or Wide Area Network (WAN), even small industrial networks tend to have a hierarchy three or four levels deep. For example, the connection of instruments to controllers may happen at one level, the interconnection of controllers at the next, the Human Machine Interface (HMI) may be situated above that, with a final network for data collection and external communication sitting at the top.