With today's global economic crisis, the automation sector is looking to increase the efficiency of its plants while keeping costs down. As automation engineers and plant managers strive to optimize their systems, they are increasingly turning to IT technologies to get real-time information from the factory floor. Consider the benefits of using wireless networking, Ethernet, and Web services.
The key to getting plantwide real-time data is communication between the machines on the factory floor and in the enterprise. As wireless networking has become more commonplace, its performance, reliability, and security has matured to make the technology viable for industrial measurement and monitoring applications.
The desire to minimize cabling costs and the difficulty of running wires to every nook and corner of a plant have resulted in industrial automation's slow march toward wireless technology. Engineers and managers have quite a few wireless standards at their disposal, from 802.11 (Wi-Fi) to ZigBee. Although Wi-Fi networks have become standard fare in corporate offices, offering good speed and flexibility, a ZigBee network is better suited for control and monitoring applications because of its lower power consumption and cost.
One major concern of users is the security of the network. With data being transmitted over radio waves, there are few means of physically restricting network access. Both Wi-Fi and Zigbee, however, use 128-bit AES encryption. This measure is so strong that the National Institute of Standards and Technology recommends its deployment by government installations. With hardware vendors choosing one standard over the other, it's important that you choose open and flexible software that can communicate with a number of wireless standards.
There's also value in a hybrid network topology that combines Ethernet with wireless networking. Ethernet has been widely adopted in the IT and automation sectors, so it's easy to connect gateways that collect data from wireless sensors and data acquisition devices to the existing infrastructure. Many industrial fieldbus and communication standards, such as Ethernet/IP, EtherCAT, PROFINET, and Modbus TCP, use the Ethernet physical layer. Keep in mind that, even though these protocols use the same physical layer, you need fieldbus gateways that map one protocol to another.
Consider Web service–enabled programmable automation controllers (PACs) deployed throughout your plant or even across multiple plants. When a machine drifts away from optimal operating parameters, you can log into the PAC and control the machine remotely, using a laptop or a smart phone's browser to get real-time data and fine-tune the machine.
Web services enable the invocation of a service from a remote target, using standard Web-based protocols. In the example mentioned above, a Web service running on a PAC receives requests from thin clients running on Web-enabled devices and responds with the appropriate information. The information is then interpreted and displayed on the client-side application.
You rely on this communication method for everyday activities, such as browsing the Web, checking emails, and even reading this essay online. Although the method is good for monitoring applications, it does have limitations. For example, it's not ideal for high-speed data streaming applications because the client must issue a new request every time it wants updated data. Under these circumstances, it's impossible to guarantee how quickly data will be returned because of the quality of the connection, availability of bandwidth, and proximity to the server location.
It is not outrageous to suggest that automation engineers can set up wireless measurement and monitoring systems or even manage Web services with minimal help from their IT department. The ability to use existing networking infrastructure and choose hardware and software that are open and flexible enough to take advantage of these IT technologies is very important, as the line between IT and automation begins to blur.