Wireless LAN
High-performance wireless networks offer increased flexibility and mobility
Wireless Local Area Network, WLAN for short, denotes a wireless, local network that is based on the IEEE 802.11 standard and is compatible with wired Ethernet.
It is therefore often referred to as Wireless Ethernet. In Ethernet-based automation networks such as PROFINET RT, EtherNet/IP™ or Modbus/TCP, Wireless LAN enables automation devices to be integrated wirelessly.
The IEEE 802.11 standard
The different technologies are specified in a group of standards: IEEE 802.11. The most important standards from IEEE 802.11 are:
- IEEE 802.11a: transmission standard in the 5 GHz band with up to 54 Mbps
- IEEE 802.11b: old transmission standard in the 2.4 GHz band with up to 11 Mbps
- IEEE 802.11g: transmission standard in the 2.4 GHz band with up to 54 Mbps
- IEEE 802.11n: latest transmission standard in the 2.4 GHz and 5 GHz band with up to 600 Mbps
- IEEE 802.11i: latest security standard, also known as WPA2
- IEEE 802.11e: defines the Quality of Service functions (QoS)
Comparison of the achievable data rates of the WLAN transmission standards
The main difference in the standards is the data rate that can be achieved, whereby the effective achievable net data rate is only around 50% (see graphic).
Large networks with several devices
Wireless LAN is characterized by the fact that, as is the case with Ethernet, large networks can be constructed with several devices. In contrast to wired Ethernet, however, this wireless medium is a so-called shared medium, which must be shared by all devices in the network or frequency band.
This results in longer latencies, increased jitter, and, generally speaking, a reduced bandwidth the more devices there are in the network in comparison to a wired connection. These factors must be taken into account when planning the automation application. The industrial WLAN products from Phoenix Contact are optimized for short latencies with low jitter.
Roaming - mobility in the network
One particular strength of Wireless LAN is the mobility of the devices in the network. The devices in a large WLAN network can move freely and therefore switch their wireless connection automatically to the access point with the best wireless signal. This process is known as roaming.
The wireless field of a WLAN network can be infinitely extended through the use of additional access points. The speed and reliability with which the devices - so-called WLAN clients - can switch cells is decisive in automation applications. Fast and reliable roaming is a quality feature of industrial WLAN products from Phoenix Contact.
High performance with high reliability
The latest Wireless LAN systems according to the IEEE 802.11n standard offer a considerably higher data rate of several 100 Mbps in comparison to older WLAN standards together with a longer range and increased reliability.
MIMO uses reflections and multipath scattering for increased reliability and a higher data rate
The most important technical feature of IEEE 802.11n is the MIMO (Multiple Input, Multiple Output) antenna technology. It sends and receives several parallel streams of data at the same time via up to three active antennas. As such, reflections in the room are used in a targeted way to increase the data rate and improve the reliability and stability of the wireless connection, particularly in industrial environments.
Application examples
Wireless LAN's areas of application in industrial environments are diverse and on the increase. The increasing need to communicate process and operating data together with the increasing mobility and remote nature of numerous applications rely on the use of wireless network communication.
Flexible autonomous transport systems in intralogistics
Shorter delivery times and diminishing quantities do not only represent a huge challenge to online shops and the associated logistics service providers. Autonomous transport systems, warehouse shuttles, and carry systems that move independently in the plant increase flexibility and improve efficiency.
Industrial Wireless LAN systems are the solution for reliable communication between central controllers and carry systems. Discover the possibilities with Industrial Wireless in intralogistics:
- Fast roaming
- Realtime communication between the controller and carry system
- Sufficient reserve even for data-intensive applications
(Image source: Grenzebach Maschinenbau GmbH)
Smart devices in factory automation
In the private domain, tablets and smartphones are now the norm. Now they are having an ever stronger impact on industry: users also want to use their smart device for operating data acquisition and diagnostics, and sometimes even for the programming and operation of machines and systems. Benefit from industrial wireless systems for:
- Convenient visualization of machine data on smart devices
- Easy and efficient remote maintenance with smart devices
- Intuitive control and operation via smart devices
(Image source: Asys Automatisierungssysteme)
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