Using laser scanners to safeguard your workforce
Safety laser scanner operation
Connecting multiple safety laser scanners For large detection areas IDEC has the SE2L-H05LPC safety laser scanner (Figure 3). It has much of the same features as the SX5-B with the added advantage of being able to connect four SE2L scanners acting together. The SE2L-H05LPC connects to the local network using a waterproof 100Base-T Ethernet connector and is configured from a host PC using a USB 2.0 connection. Alternatively, configuration data can be transferred to the SE2L using a micro SD memory card. This makes transferring a new configuration to a different SE2L unit very fast and efficient by not having to connect it to a PC. The SE2L is 95 mm high, making it easy to fit in small areas. The detection angle is 270 degrees with a maximum detection range of 5 m. It can filter out ambient light and is rated at IP65, preventing dust ingress and making it more resistant to false detection events. For monitoring large floor areas, up to four SE2L scanners can be connected together. One host SE2L is connected to the main control board or programmable logic controller (PLC) responsible for the equipment and the scanners. Up to three more SE2L scanners are connected to the host scanner’s RS-485 port. An alarm or event indication on any of these three SE2L scanners is communicated
Safety laser scanners have a built- in detection algorithm that uses a programmable laser sampling rate to verify intrusions. Most scanners are set at the default sampling rate of 2x to verify an object—that is, the object must be detected twice in a row to trigger an action. Multiple sampling prevents foreign particles such as metal shards or insects from triggering a false alert. Increasing the number of samples decreases false positives but also increases detection time. If the detection time is increased, safety can be maintained by increasing the detection distance, allowing more time to provide an alert. A rugged safety laser scanner designed for large industrial environments is the Banner Engineering SX5-B safety laser scanner (Figure 2). The SX5-B has a maximum range for safety and warning zones of 5.5 meters (m) and 40 m, respectively, and connects to the facility’s wired Ethernet using an M12 connector. It is IP65 rated, making it immune to dust and water sprays. The laser receptors filter out visible light, making it immune to ambient light interference. The SX5-B can be configured for up to six zone sets— for example, five warning zones and one protection zone. The SX5-B has a color LCD display to indicate the status of the safety laser scanner. The display can
to the host scanner over the RS- 485 connection. The host then communicates the appropriate action to the PLC or to any of the alarm indicators. This allows all four scanners to share common alarm and alert indicators for their individual detection areas. This greatly simplifies configuration and reduces wiring. Conclusion Keeping human operators safe is a top priority in industrial automation facilities. Some areas are too hazardous for people to access while equipment is operating, but at the same time human operators need easy access to the equipment when it is not operational. Safety laser scanners provide an easy and effective means of monitoring the floor area around hazardous equipment. This improves productivity by keeping human operators safe while allowing the equipment to be easily accessible when required during normal operation. Figure 3: The IDEC SE2L-H05LPC safety laser scanner supports a 270-degree protection field for up to 5 m. Four SE2L scanners can be easily connected together using RS-485 for simultaneous operation. (Image source: IDEC)
indicate up to 27 different status, diagnostic, and error conditions including a warning or protection violation, or indicate if the laser detectors need to be cleaned. The SX5-B has a 275-degree protection field and can continuously scan the protection area for intrusions in the monitored area. The scanner can filter out false positives from dust, dirt, or small debris. It is 152 millimeters (mm) high, making it easy to position in a busy area without interfering with factory operations. The configuration software is easy to use and allows flexible detection areas to be laid out including rectangular, circular, or irregular shaped. This flexibility allows the SX5-B to safely monitor only the area of concern, while excluding safe areas where an intrusion alert is not needed. Figure 2: The Banner Engineering SX5-B safety laser scanner has a maximum range for safety and warning zones of 5.5 m and 40 m, respectively. It can provide 275 degrees of coverage and is immune to ambient light and dust. (Image source: Banner Engineering)
Figure 1: A typical safety laser scanner setup consists of two warning zones that issue alerts during an intrusion, and a protection zone that puts the equipment in a safe or non-operational condition during an intrusion. (Image source: IDEC)
facility. This is especially true when using safety laser scanners. These scanners flood a selected area with multiple focused lasers, and the laser light is reflected back to receivers on the scanner. The scanner uses this reflected light to create a two-dimensional line-of- sight map of the floor area in the scanner’s detection region. If a laser beam in the scanned area is broken, the safety laser scanner can detect the event a nd be programmed to set off warning lights and alarms, or even disable automated equipment. This keeps human operators safe while increasing machine uptime, improving the productivity of the facility. The entire area to be scanned must have a clear line of sight to the safety laser scanner (Figure 1). If the work area is not planned for a safety laser scanner from the
beginning, the scanned area might contain objects in the path of the beam creating blind spots for the scanner beams. Worse, the scanned area might contain large and non- movable obstructions like a load- bearing pillar. These obstacles can be avoided if the industrial facility is designed from the start with safety laser scanners in mind. The work area should be set up for a safety laser scanner in mind from the beginning. A technician programs the scan zones into the scanner using the visual planning software that comes with the scanner. As seen in Figure 1, the area is usually programmed with one or more warning zones and a final protection zone. Each warning zone can be set using configuration software to set off an alarm or alert. Trespassing into the protection zone can be set to shut down the equipment.
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