Device-level benefits of industrial Ethernet
An industrial enterprise can grow too big for efficient automation control using traditional technology. Advances in industrial Ethernet, however, can provide a solution. Using additional techniques such as smart remote I/O and peer-to-peer technology can result in better and more flexible control, along with a change in the way Ethernet is used.
For one quick example of the benefits possible, consider a site with widely scattered oil tanks. Monitoring the level in those tanks is best done with remote Ethernet-based smart I/O modules. Polling the tanks one by one to get their level works but the amount of time needed increases with the number of tanks. Smart remote modules with peer-to-peer capability can send a message to a control room if the level in a tank is lower or higher than a set point. The effect is a real-time update, done in a cost-effective way that scales easily with increasing site size.
For end users, having Ethernet everywhere in the enterprise means the first two layers of the standard seven-layer communication model (the physical and data link layers) are the same throughout the enterprise. This eases the task of network integration and helps with network configuration and reconfiguration. It also means that one skill set can handle the entire network, reducing or eliminating the need to maintain specialized technical expertise for other networking technologies.
Smart I/O among peers
In the traditional master-client mode found in serial and proprietary networks, a controller has to read input module data. It then sends data back to the output module, completing the input-output loop. Those transactions require a controller, along with wiring to and from the I/O module. This back-and-forth sequence can take extra time if the controller is busy with another task. It also can be difficult to scale for a variety of reasons. It may involve a proprietary network, which may only be able to cover a limited distance. Likewise, there could be scaling problems if the number of connections to the controller overwhelms the device or proprietary protocol.
Peer-to-peer can decrease wiring
In contrast, peer-to-peer connections run from specific input channels on one module to specific output channels on another. Data automatically transfer from one to the other, simplifying the entire I/O process. One obvious advantage is that no controller is needed, saving system hardware costs. A less obvious benefit is that the wiring can be simplified, since it need only run from one module to the next. If connections are done using industrial Ethernet, then the wiring options become very flexible.
For an example of how peer-to-peer technology can help solve some real world problems, consider a company with three branches in separate countries. At headquarters, personnel in a control room monitor the gates leading to the other sites over an Internet connection. Given the desire to actively control the gates, one solution would be to run a separate communication network. With peer-to-peer modules, however, that control can be done over the existing intra- and Internet by placing a module at the control room and each gate. The control room module can act as a controller for each gate through the remote module.
Of course, there are different ways to implement peer-to-peer connections. One is to simply map the channel of one module to another, ensuring the security and pairing of the connection by only allowing a specific IP or MAC address control authority. The other is a more advanced case, with multiple modules mapping to one on either the input or output side. Advantech’s Adam series of controllers offer such a capability. They enable flexible channel mapping while offering a response time of less than 1.2 milliseconds for wired modules and less than 30 milliseconds when in an ad hoc wireless mode.
To see more resources, including the full whitepaper “Benefitting from Industrial Ethernet at the Device Level with Smart Remote I/O and Peer to Peer Technology,” visit www.controleng.com and search “Industrial Ethernet.”
|Peishan Juan is a technical writer with the Industrial Automation Group of Advantech Corp.|