PDF1. Programmable Automation Controllers and Wireless Technologies
While wireless technologies are changing the world of communication and measurements, leading measurement and automation companies are working to improve the flexibility and performance of measurement and control systems. New classes of industrial controllers known as programmable automation controllers (PACs) combine the ruggedness and reliability of a programmable logic controller (PLC) with the flexibility and performance of a PC under an open software architecture. With these controllers, you can build advanced systems that integrate software capabilities, such as advanced control, communication, data logging, and signal processing, with rugged hardware performing logic, motion, process control, and vision. By combining the flexibility and performance of PACs with wireless technology advances, engineers are creating new industrial measurement and remote monitoring applications including the following:
• Industrial machine condition monitoring
• Industrial health monitoring
• Embedded data logging
• Environmental monitoring
Figure 1. NI PACs
2. Industrial Wi-Fi Wireless Access Points
The broad adoption and deployment of Wi-Fi devices based on IEEE 802.11 has resulted in the availability of Wi-Fi access in homes, businesses, and plants. The openness and speed of Wi-Fi make it an industry standard for wireless communication between PCs and the network at an enterprise layer. Security protocols including IEEE 802.1X authentication and Wi-Fi Protected Access (WPA) help address security concerns, and the ease of use and bandwidth increases of IEEE 802.11 have sped up Wi-Fi adoption. Because NI LabVIEW software and PACs support open industry standards, industrial systems also benefit from the broad adoption, ease of use, and speed of Wi-Fi. However, deploying Wi-Fi in industrial environments requires rugged hardware beyond that available in the commercial market. Industrial Wi-Fi devices combine the best features of the Wi-Fi standard with the rugged packaging and specifications required for industrial applications. NI wireless access points (WAPs) offer Wi-Fi access based on the IEEE 802.11g/b standards in two versions: the NI WAP-3701, which supports power output and frequencies required by the FCC in the United States, and the NI WAP-3711, which supports the power output and frequencies required for operation in Europe and other countries. The WAP-3701 supports the IEEE 802.11 North American 2.4 GHz band with channels from 1 to 11, and the WAP-3711 supports 2.4 GHz international frequency bands with channels 1 to 13.
Figure 2. Industrial Wi-Fi Point (WAP)
3. Case Study: Wireless Access Points and PACs
In the case study, “Researchers Use NI LabVIEW and CompactRIO to Perform Environmental Monitoring in the Costa Rican Rain Forest,” the Center for Embedded Networked Sensing (CENS) at UCLA used LabVIEW software and CompactRIO hardware to develop a wireless sensor system that collects a variety of environmental measurements, offers remote configuration capabilities, permits future expansion, and gives researchers around the world access to the measurements over the Internet. The center implemented the system using NI modular hardware and the additional communication and configuration advantages of LabVIEW. Engineers selected CompactRIO as the central measurement unit and the NI Compact FieldPoint network interface with NI cFP-180x controllers for distributed wireless measurements. They also chose the NI WAP-3701 to transfer data between the distributed sensors, towers, and canopy floor.
According to Dr. William Kaiser at UCLA, “Because of the flexibility of LabVIEW, we can configure measurement types, select channels, and even add scaling from a laptop connected to the system.”
4. Wireless Access Point, Client, and Bridge Functionality in a Single Device
A WAP-37x1 functions in three modes: access point, client, and bridge. When a WAP-37x1 is in access point mode, it works as a Wi-Fi link to an Ethernet access point that provides connectivity from a host PC or PAC to several client PAC systems, as shown in Figure 3. A WAP-37x1 also functions as a bridge that connects remote devices to an access point, which extends the total range for a wireless system.
Figure 3. An NI WAP-37x1 as an Access Point, Bridge, and Client
5. WAP-37x1 Industrial Features
NI WAPs offer a dual-redundant power supply with a 12 to 45 VDC input range. They are rated for 0 to 60 °C operating temperature and feature an IP30-rated metal enclosure for deployment in harsh environments. They offer Class I, Division 2, and ATEX certifications for hazardous locations, and support DIN-rail and panel mounting.
6. LabVIEW Compatibility with Wireless
LabVIEW is an open graphical development environment that works with a wide range of industry standards including Wi-Fi. Wi-Fi and Ethernet are supported at the Data Link and Physical layers in the Internet Protocol Suite. LabVIEW communicates data over Wi-Fi, based on the IEEE 802.11 standard, in the same way it passes data over wired Ethernet, based on the IEEE 802.3 standard. LabVIEW and the compatible Ethernet-based protocols, including TCP/IP, UDP, and shared variables, work seamlessly over Wi-Fi connections.
7. Extending PAC Measurements
Figure 4. NI WSN devices extend measurement capabilities of existing PAC devices
In addition to combining existing PAC measurements with an access point, you can also extend your measurements using the NI Wireless Sensor Network (WSN) platform. The NI WSN Ethernet Gateway can be cabled directly to your PAC, allowing you to connect up to 36 wireless measurement nodes to your existing system. The nodes can be placed up to 300m away from the gateway, allowing you to create a fully integrated wired and wireless measurement and control system. To learn more about WSN product and configuration options, read the whitepaper.
8. Conclusion
Today, Wi-Fi access is commonly found in homes, businesses, and factories. By combining the availability of Wi-Fi with the processing and embedded performance of real-time hardware, wireless PACs can help you solve many application challenges. LabVIEW offers compatibility with wireless Wi-Fi and wired Ethernet communication, so you can easily add wireless access to PACs.
