Industrial Wireless Equipment
Industrial Wireless Local Area Networks (WLANs) are designed to operate over the same local area network range and have many of the same features, however, WLANs are more reliable. Certain protocols are implemented to make real-time communication failsafe and roaming can be 10 to 100 times faster than regular Wi-Fi. WLAN antennas and radios are designed specially to operate using WLANs and are capable of performing in remote and harsh environmental conditions.
WLAN antennas are devices that redirect energy they receive from a transmitter, providing more energy in one direction versus all other directions. Antennas can generally be classified as omnidirectional and directional. Omni antennas radiate and receive radio frequency (RF) energy equally in all horizontal directions. This broad coverage area increases the probability of maintaining connection stability, however the potential for interference and lower throughput is more likely. Yagi antennas radiate and receive RF energy in a selected direction, usually around 45 to 90 degrees. The signal from the target area is improved through directivity gain as long as there is no congestion. Interference is held to a minimum.
WLAN radios are industrial radios used for wireless transfer of data. Each model of radio has its own communication protocol which does not allow communication across brands. The three most common data radios are Serial, IO and Ethernet. Serial radios have one master radio that communicates with slave radios in the same network. Each network can have only one master radio that polls the slave radios one by one. Each slave radio has to wait for the master radio to poll it in order to send and receive data. For this reason, serial radios are a slower form of communication and could take several minutes to communicate. IO radios are designed to transmit and receive small amounts of data and allow various signal types to be wired directly into the radio. In most cases, wireless IO radios must be used in pairs, where one radio transmits the data and the other radio receives the data. Ethernet radios have an Access Point radio in a network that communicates to a number of remote radios. Each network has only one Access Point radio communicating to a number of remote radios sending and receiving data at any time without being polled. Data is sent in packets over several frequencies resulting in faster communication.
Products
There are many different communication protocols that can be used when selecting a radio. The type of protocol being used may depend on the application, time frame the hardware was installed, existing hardware that is already in place and many other factors. What is important to understand is that most of these protocols fall into two generic families: Serial-based protocols or Ethernet-based protocols. Examples of Serial-based protocols include: Modbus RTU, RS-232, RS-485 and Profibus. Examples of Ethernet-based protocols include: Modbus TCP, Ethernet IP and Profinet. The differences that exist in these protocols has a lot to do with data transmission speeds.
Serial-based protocols have a much more limited data transmission capacity compared to Ethernet-based protocols, however, they do not require a connection strength as strong as Ethernet-based protocols. This is beneficial in situations where the radio connection may be limited because of physical obstructions or long distances. Ethernet-based protocols have faster data transmission capabilities and are becoming much more common than Serial-based protocols. By understanding the differences between these two types of protocols, you will be better equipped to select the radio that will work best for your specific application.