Arm Yourself with Wireless Know-How for the Industrial IoT Age
Although the “Internet of Things” (also known as the IoT, and the “Internet of Everything”) has been around for many years, global deployment of IoT networks has rapidly increased within the past 12 months. We can see companies starting to realize this concept in products that can be used in daily life from grocery shopping to automated guided vehicles to smart homes and smart cities. The IoT essentially centralizes data through wireless technology and uses machine learning or big data analysis to turn the data into valuable information. The scope of the IoT is huge and a new IoT subset—the Industrial Internet of Things (IIoT)—has since surfaced. The Industrial IoT essentially brings the world of the IoT and its latest technologies to legacy industrial applications in order to reduce costs, increase productivity, and maximize uptime. So, are you ready for the Industrial IoT age, or are you still fighting a tank with a knife?
Before you can analyze data, you first need to collect it. Generally speaking, wireless communication is the fastest and most cost-effective solution for large-scale wide-area data collection. It is also the only viable option for rolling stock applications for which communications devices are always on the move. Even though wireless technologies have been around for more than 20 years, many people are still afraid of using wireless solutions due to the technology’s complexity and instability, as well as a general lack of understanding. In this article, we will explain some of the common challenges our Industrial IoT customers have encountered so you can arm yourself with sufficient wireless knowledge to enter the Industrial IoT age.
Challenge #1: Open Field and Indoor Factory Environments
Open Field Environments
Networks in oil and gas, open-pit mining, harbor, water/wastewater treatment, and smart bus applications usually need wireless access points or clients in an open field. Incorrect installation often results in device damage or performance degradation. We commonly see two main errors that can create hazards:
- Device Damage Caused by Direct Lightning Strikes on an Antenna
In order to obtain good wireless coverage and line of sight, it is recommended to install wireless access points as high as possible. However, if the devices are installed in an open field and the antenna happens to be the highest spot, it is likely that lightning will directly strike the antenna and cause permanent damage to the wireless access point. Professional firms can be hired to install expert lightning protection to protect your devices from lightning strikes.
- RF Damage Caused by Coupling Currents
Even when lightning is captured by lightning rods, the coupling effect will still transfer enough current to the antenna and RF cable to gradually damage the RF performance of the access point. In order to prevent the coupling current from damaging the device, lightning arresters and DC blocks are commonly used in RF systems.
Indoor Factory Environments
In smart factory applications, such as automatic warehousing, sometimes the wireless clients must be installed next to a generator or motor, such as when a wireless client is deployed on an automatic guided vehicle (AGV). One common problem we see is when wireless clients are connected to the same power supply as the motor; the inrush current and the unstable voltage from the motor can cause device instability and even permanent hardware damage.
Separating the power supplies for the motor and other equipment is the most effective solution. However, there are times narrow installation space and budgetary constraints will not allow an extra power supply. In this case, devices with galvanic (power) isolation will be required.
To simplify installation, the new AWK A series is designed with integrated dual isolation protection. First, Integrated RF Isolation provides 500-V insulation protection and level 4 ESD protection, without loss of the RF signal. In addition,Integrated Power Isolation provides 500-V insulation protection and stabilizes system voltage.
Products that Support Dual Isolation: AWK-1131A, AWK-3131A, AWK-3191
Challenge #2: Wireless Interference Problems
Wireless communication’s greatest enemy is wireless interference. In order to provide stable wireless communications, site survey and channel planning are always required. Wi-Fi (802.11x) communication is based on CSMA-CA (Carrier Sense Multiple Access with Collision Avoidance), in which all devices using the same frequency (channel) share the overall bandwidth. For example, if you have one DLink AP, one Cisco AP, and one Moxa AP that are all using channel 6 at a frequency of 2.4 GHz, the overall bandwidth will be shared by all connections connected to these three access points. Therefore, when the frequency (channel) is fully occupied, important data might be delayed or lost.
Consequently, a frequency of 2.4 GHz is not recommended for Industrial IoT communications over wireless networks. The frequency available for 2.4 GHz only allows three non-overlapping channels. With commercial access points and smart phone hotspots everywhere today, 2.4 GHz channels are likely to experience interference.
Based on prior experience, the 5 GHz frequency band tends to be cleaner and provides better communication for operational data. Due to overcrowding on the 2.4 GHz frequency band and the introduction of 802.11ac, many people have already begun migrating to 5 GHz. Likewise, some industrial users are also moving to 5 GHz DFS channels. With DFS channel support, the 5 GHz channels available will be increased from 4 (7 for the US) to 20 (27 for the US) channels. Even though DFS channels need to give way to radar signals, DFS channels still provide a cleaner air space for communications.
Products that Support DFS Channels: AWK-1131A, AWK-3131A (available Q4 2015)
Challenge #3: Interoperability with Existing Factory Equipment
For many existing wired SCADA systems or other networks, MAC-authentication, or Layer 2 (MAC-based) communication, is sometimes used for network security. However, due to the limitation of the standard 802.11 AP-Client protocol, MAC addresses for devices behind a wireless client are often replaced by the client’s MAC address, and vice versa. In order to overcome this limitation, Moxa has developed “MAC Clone” technology to allow the device behind the wireless client to maintain its own MAC address.
Products that Support MAC Clone: AWK-1121, AWK-1131A, AWK-3131A
Challenge #4: Seamless Roaming for Mobile Communications
Unmanned AGVs and shuttles commonly implemented in factory automation applications allow operators to benefit from lower costs and higher efficiency. To avoid wiring and space constraints, operators should consider products that support seamless wireless roaming to control and monitor these mobile applications.
In mobile applications that involve multiple access points (APs), roaming (also called handover) refers to when a client moves between two or more access points, and the speed of the mechanism used to effect the roaming mechanism can be crucial to a project’s success. As the client physically moves from one AP to another, the signal strength of the first AP will drop while the signal strength of the second AP will increase. A standard roaming mechanism only starts scanning for the second AP when the first AP disconnects, which can take 3 to 5 seconds or more to process. Such a long handover time can result in packet loss, which could cause serious damage from unmanned AGVs that have temporarily lost the connection to their control signal.
To avoid packet loss, operators need a seamless roaming mechanism that actively searches for APs with a stronger signal, without waiting for a complete disconnection. Seamless roaming offered by Moxa’s Turbo Roaming technology can reduce the handover time to the millisecond level and provide the benefits of seamless transmission and control.
Products that Support Turbo Roaming: all AWK Series
Challenge #5: Constructing a Redundant Wireless Bridge
In industrial applications, such as communications between offshore oil platforms or train-to-ground communications, a reliable wireless bridge is essential to minimize system downtime and maximize system availability. Moxa’s AeroLink Protection provides a reliable wireless bridge between two networks. An old-fashioned wireless bridge or WDS connection exposes the link to at least one of two types of risks: device failure and wireless link failure.
In order to prevent a single point of failure from bringing down an entire wireless network, AeroLink Protection constantly monitors each device’s status. If the active node is disabled by a local power failure or hardware fault, the backup nodes will automatically take over to keep the data moving.
Wireless Link Failure
1. Communication Failover: AeroLink Protection allows devices to negotiate with each other to automatically select an active node for data communication and render other nodes as backups. Later, if the active node is no long capable of sending data to its access point, the other nodes will quickly renegotiate to resume communication via another path.
2. Frequency-Interference Failover: This concept works similarly to (1) above. If there is interference on the active communication frequency and data can no longer be transmitted, the network swiftly and automatically restores the connection via a backup frequency.
Scalable Network redundancy technology
AeroLink Protection is designed to allow almost unlimited backup paths. Therefore, users can create a completely redundant wireless network, safe from all the above failures. Besides, AeroLink Protection is designed to restore communications within 300 ms of any failure avoiding seriously interrupting communications when a failure occurs.
Products that Support AeroLink Protection: AWK-3131A
Download our white paper on wireless bridge redundancy to learn more
Moxa’s Solution—AWK A Series
Moxa’s new AWK-A series is designed to conquer all challenges from installation to operation. Visit our web site for more information on how the AWK-A series ensures unbreakable wireless networks for your Industrial IoT applications.
|A Series Models||AWK-1131A||AWK-3131A|
|Integrated Dual Isolation|
|Client-based Turbo Roaming|
|DFS Channel Support||Available Q4|