Wireless network systems continue to move into discrete applications. But the installation process is still not plug and play simple. Answers to the following questions will help smooth the process.
Before installing a wireless network in a factory, you should be able to answer the following questions: Will the radio signal reliably transmit within your facility? Can you choose products that are easy to install? Can your facility accommodate the power requirements of the wireless components? Will the wireless products communicate with your existing plant-wide network?
If wireless technology is small and contained within its own waterproof housing, the wireless components and their sensors are easy to install.
With wireless systems, you can improve production through the ability to wirelessly call for parts, detect parts moving from one work station to another, count parts exiting or entering work stations, and monitor machine status and throughput for work flow productivity analysis.
1. Will the radio signal transmit far enough to reliably exchange data in your facility?
Many radio specifications are listed in miles, but these specs are typically based on best-case scenarios, perfect weather conditions, and the assumption that there are no obstacles in the line of sight. Don’t assume a radio system can reliably transmit radio signals in every environment—especially an indoor manufacturing space—without first testing the range of the wireless components in multiple locations. To be thorough, you should test every planned radio location. Any potential obstacle may affect how consistent your network signal will be.
For the most accurate results, look for radio products that offer integrated received signal strength indictor (RSSI) capabilities. RSSI tools not only let you test the radio signal strength before permanently installing the radios but also throughout the life of the product, enabling you to optimize the performance of the network by installing radios in the best possible location. As the plant configuration changes, re-testing the radio signal strength with the RSSI tool ensures the radio components can be easily moved while maintaining the network’s performance.
Many discrete manufacturing facilities require data to be transmitted between buildings. Depending on the obstacles in these outdoor applications, it may be necessary to run the radio signal strength analysis several times a year to account for different seasonal conditions. In some cases, signal strength can even vary depending upon the density of trees and other foliage between buildings.
Indoors, you may need to re-run the signal strength analysis if your facility’s configuration changes. When RSSI tools are built into the wireless system, you can run the analysis without interrupting the overall function of your network.
2. Is the product easy to install?
Some wireless systems are modular, requiring a radio, power supply, and I/O terminal block be wired together and then installed inside a separate enclosure. Adding many components can result in a clunky system that is more of a challenge to install or move.
Look for a less modular approach if your wireless components need to be moved as the plant configuration changes. When wireless technology is small and contained within its own waterproof housing, the wireless components and their sensors are easy to install. And if your facility configuration or your application needs change, smaller wireless products are easy to move to new locations. Portability is particularly convenient for preventive maintenance motor monitoring; after one motor or set of bearings has been monitored, a user can move the wireless solution to another problem area.
For parts counting applications, wireless systems give managers a way to accurately measure and report machine run time. In a welding facility, operators load a welding machine with frame components. When the components exit the cell, the operators unload and then load more components in preparation for the next cycle. A wireless network tracks and reports machine run time.
3. What are the power requirements?
In a production facility, finding the appropriate power is rarely a problem, but wiring power to a wireless radio may be cumbersome and inconvenient. For some applications, the use of existing dc power to operate your wireless network works well. Other applications may be more convenient to power from a compact and portable power supply, such as a battery pack. Several wireless networks can be powered from both dc power and a battery pack.
Wireless products designed for flexible power use are also optimized for a relatively long battery life. When you know your battery’s approximate lifespan, battery replacement can be easily conducted as part of your annual maintenance schedule. And if know the power characteristics of the sensor and the radio, you can perform rough calculations to estimate how long your battery pack will last before it needs to be replaced.
For some outdoor applications, powering the radio from a solar panel is a viable option. But not all sensors can be powered from limited or intermittent sources. If it is possible you will need to use batteries or a solar panel as a power source; make sure you know the power requirements or limitations of the sensors you will be using.
4. Will these Wireless components communicate with the existing plant-wide network?
Many manufacturing machines already use Modbus or another standard serial communication protocol to communicate through wired connections. If your wireless technology needs to communicate with machines and collect or concentrate data onto a plant-wide network, look for wireless products that communicate over Modbus, EtherNet/IP, or Modbus/TCP.
Some wireless technologies also allow plant managers to access data remotely from any computer with access to the Internet. These systems are password protected and usually require a secure Internet connection to ensure plant information is not hacked or stolen.
5. How large do you think your wireless network will be?
Some wireless systems are meant to collect and exchange data from only two points, while others can work with data from a dozen or more points. Also, while most wireless systems allow multiple networks to exist close to each other, some require a separation of the radio signals.
Before investing in a wireless system, investigate your current situation, and also the possibility of future network expansion. If you think your network may expand, look at wireless units that allow you to easily add data collection points. If you think you may need multiple standalone networks, make sure your wireless approach will let you co-locate networks without unwanted data exchanges or signal interference.
Discrete applications for wireless data collection: Most manual data collection can be replaced with a wireless network to eliminate human error. Instead of waiting for data that may only be collected a few times a day, a wireless network of sensors can collect and report data in seconds.
Call for parts: Wireless call-for-parts applications often include indicator lights to offer a quick and visual way to show when a line worker needs work or parts. One common call-for-work application uses a small wireless network at each workstation. Production workers press one or more buttons to indicate that they are getting low on work.
In call for parts applications, as production workers begin to run low on supplies, they can wirelessly signal the forklift to make a delivery—without having to stop their work or leave their station.
Facilities that use this type of call-for-work notification typically save time: the production worker or supervisor no longer needs to walk the production floor to assess work needs, and employees are assigned more tasks before they actually run out of work.
Another call-for-parts solution installs battery-powered wireless products, buttons, and lights at workstations and on forklifts that deliver supplies. As production workers begin to run low on supplies, they can wirelessly signal the forklift to make a delivery, without having to stop their work or leave their station. Once the driver makes the delivery, he presses a reset button to turn the indicator lights back to the “no delivery needed” state until the next time a supply run is needed.
Machine status or production counts: Many production facilities count parts entering and leaving machines during production runs. Counting these parts lets supervisors gauge workflow and calculate production efficiencies. Logging the length of time a machine is in operation can also be helpful in estimating machine maintenance needs.
One useful parts-counting application was used in a welding facility. Operators loaded a welding machine with frame components, and the robot completed the welding cycle. When the frame exited the cell, the operators unloaded it and then loaded more components in preparation for the next cycle. When production goals were not being met, operators blamed machine downtime, and maintenance personnel blamed operators for working too slowly. The facility needed to accurately measure and report machine run time back to a control location to determine the real problem.
PLC logic and wireless devices were installed to resolve this problem. The system logged every time the machine started and stopped, indicating exactly how long the machine was used. This accurate work time count was wirelessly transmitted back to a central control location. Based on real-time data collection, the facility managers accurately verified when the delays resulted from machine down time and when they resulted from operator inefficiency. With accurate information about the production delays, plant managers improved efficiency and decreased machine downtime.
A similar parts-counting application was used to streamline a printing facility. By gathering machine count data in real time instead of waiting for a report at the end of the month, supervisors were able to better use idle machines, and operators were able to correct per-job efficiency numbers sooner. Thanks to the wireless technology’s instantaneous data capture and calculation/display, plant management had information at their fingertips on which they could base capital equipment and personnel investments decisions.
Filed Under: Wireless, Networks • connectivity • fieldbuses, Wireless devices