Sensors get smart

Adding intelligence to sensors is a definite trend in the industry. Not too long ago, users were content with just on/off contacts. Engineers now are eager to implement networks. With machine uptime a critical issue, the ability to implement diagnostics to improve maintenance response is also essential.

By Staff August 1, 1998
  • Added intelligence

  • Networking ability

  • Easier to set up and use

  • Industry-specific design

  • Diagnostic capabilities

Adding intelligence to sensors is a definite trend in the industry. Not too long ago, users were content with just on/off contacts. Engineers now are eager to implement networks. With machine uptime a critical issue, the ability to implement diagnostics to improve maintenance response is also essential. Users expect sensors to contribute to these factory improvements.

Teach a smart sensor

Mark Duncan, product line manager for Square D Co. (Palatine, Ill.), says, “New smarter sensors can learn their environment, adjust and adapt themselves to the application regardless of background or target. With this capability it is possible to detect objects more easily and precisely with less cost.”

Ron Cunningham, Eaton/Cutler-Hammer’s (Everett, Wa.) proximity sensors product manager agrees, saying, “We feel that there is a strong push to increase network and diagnostic capabilities in sensors.” Adds Larry Palmatier, sensors product manager for Cutler-Hammer, “The market continues to grow toward noncontact sensors. A big change has come because sensors are lasting longer, which helps reduce replacement costs.”

Mike Frey, product marketing manager at Omron (Schaumburg, Ill.) says, “One of the most common trends is incorporating ease-of-use and set-up features such as teaching amplifiers, push-button amps, and connector-ready sensors.”

Designed for specific applications

Balluff’s (Florence, Ky.) application engineer Tom Rosenberg sees more industry-specific sensors being developed. “Welding manufacturers need multimetal sensors, while a sensor detecting moving sheet metal in a stamping operation must discern flutter in the metal on the fly.” He notes that vendors must focus on the need to fix problems for customers.

Control Engineering surveyed 1,500 readers to find out more about how sensors are really used. Of the 294 responses, 60% worked in a process environment, 30% built machinery, and 15% were involved in discrete product manufacturing.

Sensors are being used in some very nasty environments. When asked what the typical specifications for environment and protection were, most cited washdown and short-circuit protection. Interestingly, 30% of the responses mentioned intrinsic safety as a normal specification. Reverse polarity protection and NEMA 4/4X housing were the next most mentioned specifications. Almost 10% of the respondents need weld-field immune devices.

Sensor applications

There are a variety of sensors with differing characteristics. Readers were asked the applications used for different types of sensors.

Inductive proximity sensors were primarily used in machinery (56% of the responses) with raw materials processing (22.5%) and packaging/palletizing (19.8%) applications also often mentioned. Ultrasonic proximity sensors were primarily used in fill-level (19.8%) applications as well as in machinery (18.5%). Capacitive proxes were also mostly used in machinery (26.8%) and fill-level (20.8%) while raw materials processing (19.8%) was also mentioned. Not surprisingly, photoelectric sensors were primarily used in machinery (52%) and packaging/palletizing (28%).

There was a time when almost all control in the United States was 120 V ac. The benefits of dc control are becoming more well known; the survey results showed more users buying dc sensors than ac.

Users are going to continue to see sensor vendors providing more functions and intelligence in products. As engineers are asked to provide more information and improve diagnostics, they will find that new sensor technology will help them.

Proximity sensor with teach function

Schaumburg, Ill. —E2CY proximity sensor for nonferrous metal detecting features a separate amplifier and teach mode. The user presses the teach button at setup to adjust the unit’s sensitivity based on the distance between the sensor and the object being sensed. There are three sensing heads from which to choose. The 5 mm threaded head senses up to 1.5 mm. The cylindrical, nonthreaded 8 mm head senses up to 2 mm while the 4.5 mm flat-head version has a range of up to 3 mm. Omron Electronics Inc.

Proximity family

Munich, Germany —Bero is a family of proximity switches. Laser Bero 3RG7 is an optical proximity switch using a bundled laser beam to detect and position objects. It has a range of up to 50 m. Sonar Bero 3RG64 is an ultrasonic sensor not affected by various kinds of contamination, artificial light, or condensation. It has a range of 1.5 m and is suitable for clear bottle counting. Siemens AG

Smart digital sensor

Minneapolis, Minn. —DRS digital range sensors provide measurement data precise to one micron for process control, profiling, or positioning applications. Unlike traditional laser triangulation sensors, DRS sensors are capable of analyzing variations in input and making adjustments to obtain accurate data, even from reflective, translucent, or multicolored surfaces. CyberOptics Corp.

Prox improves status visibility

Milwaukee, Wis. —Allen-Bradley Bulletin 872C WorldProx inductive proximity sensor combines increased sensing distance with a 3608 visible output indicator. The status of the proximity sensor can be seen from almost any angle and at a longer distance. Sensing distance over previous models has been increased up to 50% for 12 mm shielded and 8 mm unshielded models. Sensing distance for 8 mm shielded models has been increased up to 30%. Rockwell Automation/Allen-Bradley

Improved background suppression

Exton, Pa. —Model OGH is a diffuse photoelectric sensor with automatic setup. Packaged in a standard 18 mm cylindrical body, the sensor has an adjustable sensing range from 30 to 130 mm that is independent of target color. The unit will ignore a background that is located farther than 10% of the sensing range from the target. Model OGH uses a visible red light for aligning to the target and an infrared light for accurate sensing. efector inc.

Small prox for all metals

Florence, Ky. —Factor 1 proximity sensor has a uniform 15 mm sensing distance for any ferrous or nonferrous metal such as steel, brass, aluminum, and copper. It measures 19/16 in. x 27/8 in. long. The head rotates for orientation to one of five positions. Factor 1 is weld-field immune, ealed to IP67 rating, and protected against short-circuit and reverse polarity. Balluff

Noncontact speed sensor, 0-20 k H₂

Stamford, Conn. —SPR101 Series noncontact speed sensor can sense from absolute zero to 20 kHz. Utilizing two hall effect sensors, SPR101 will sense any ferrous metal object at a distance of 0.5 mm. PNP and NPN models are available. The output is a square wave with an amplitude equal to the applied voltage. Omega Engineering Inc.

Small photo sensor either ac or dc

Lancaster, Pa. —Model 7440 cabled photo sensor is available either with ac/dc supply voltage and relay output or dc supply voltage and dual NPN/PNP outputs. Measuring 3/4 x 2 x 2 in., Model 7440 has a range of 4 in. to 10 ft. in retroreflective mode and 12 in. as a diffuse unit. A wire-selectable Light On/Dark On feature allows remote operation from a host PC or PLC. Automatic Timing & Controls

Miniature ultrasonic through-beam

Dayton, O. —Microsonic Model SM800 is a series of miniature ultrasonic through-beam sensors. An object’s material, color, speed, or environment do not affect sensing performance. Applications include the detection of irregular-shaped, transparent, or opaque objects as well as objects with either poor reflective or fully sound-absorbing surfaces. The noncontact sensor detects objects of all colors and materials within sensing range of up to 1,016 mm. The housing is rated NEMA 4X and IP67. Hyde Park Electronics Inc.

Cylindrical photoelectric sensor

Niagara Falls, N.Y. —Optex C-Series photoelectric sensor is packaged in a metal body for durability. The through-beam style has a range of up to 15 meters with a range of three meters for the retroreflective style. A polarizing filter enables detection of reflective objects. Short-circuit protection is built-in. HTM electronics industries

Sensor learns and adjusts

Palatine, Ill. —IQ Prox has a self-adjusting background suppression as well as a 25 mm sensing range. The turret head on the limit-switch-style body can be oriented in any one of five positions. The learning mode of the Telemecanique IQ Prox can be triggered from a remote location with a dry contact or by using an integral selector. Square D Co.

Weld-field-immune sensor, 20mm range

Minneapolis, Minn. —CA40, a new model of the Uprox proximity sensor line, is a weld-field-immune proximity sensor that senses all types of metals at the same sensing range. CA40 senses mild steel, stainless steel, copper, brass, or aluminum at a range up to 20 mm. The head on the limit-switch style body adjusts to five sensing positions. Its temperature range rating is–30 to 85 °C with a housing rated NEMA 1, 3, 4, 6, 13 and IP67. Turck Inc.

DIN-rail mount photoelectric

Southington, Conn. —Baumer Electric photoelectric sensor is 12 mm wide and mounts to a DIN rail. Programmable to operate as a through-beam or diffuse sensor, its teach-in mode allows the user to adjust operating parameters with a single pushbutton on top of the unit. It is available as a single unit or two independent sensors in a single housing with no crosstalk or interference. The sensor is short-circuit and reverse polarity protected. Baumer Electric Ltd.

Teflon-coated fibers

Minneapolis, Minn. —Banner Engineering now has glass and plastic fiber-optic assemblies which are encapsulated with FEP Teflon. They withstand numerous chemicals including the acid bath present in semiconductor wafer manufacturing such as the one pictured. Standard plastic models have an operating range of–30 to 85 °C. The range for HT1 models is –30 to 125 °C. Assemblies are available in through-beam and diffuse models with a liquid level probe also offered. Banner Engineering

Inductive ring sensors

Eatontown, N.J. —Fargo Controls now offers a line of inductive ring proximity sensors. The sensors detect metallic masses passing through the ring. This type of sensor is suited for counting small parts or for detection and inspection in automated systems. The sensors have internal diameters of 5, 12, 22, 25, 30, 44, 63, or 100 mm. The plastic housing is sealed to IP65 with a temperature range of–25 to 70 °C. Available in NPN or PNP outputs and prewired or quick disconnect models, the sensors are short-circuit and reverse polarity protected and shock and vibration resistant. Fargo Controls Inc.

Compact proximity sensor for IP67

Freeport, Ill. —Ideal for environments where space is at a premium, APM Series is a three-wire dc proximity sensor with an 8 mm width. It has 2.5 mm sensing range in either top or side sensing applications. It is available in NPN or PNP output configurations with an LED indicator visible from three directions. The housing is protected to IP67 with an operating temperature range of–10 to 55 °C. Honeywell MicroSwitch

Cables survive knotting

San Mateo, Calif. —These copper-based cables place no limitations on bend radius—they can be tied in a knot. DL20’s emitting and receiving electronics are contained in the sensing heads. These through-beam sensors have a 2mm sensing head with options including smooth or threaded barrel, 31.5 in. (800 mm) sensing distance, and visible red LED. DL20/S70 “Laser-like” sensor detects objects smaller than 0.002-in. (0.05 mm). STM Sensors Inc.

Photo sensor survives harsh environments

Everett, Wa. —E58 Harsh-Duty Sensors are designed to survive high-pressure and temperature washdowns, chemical attack, abrasion, heavy vibration, and high shock. The sensor is available in through-beam, reflex, and background suppression models. These cylindrical sensors are available in 18- and 30-mm diameters with a choice of cable, micro-, or mini-connector. Cutler-Hammer/Eaton

Ball-plunger limit switch

Rockaway, N.J. —These cylindrical, single-hole limit switches have a ball plunger actuator allowing higher approach speeds. They are rated NEMA 6 and IP67 and are available in either attached cable or quick disconnect models. At 18 mm, they fit in the same hole as a proximity switch. The switches are also available in 14 mm diameter. Operating point reproducibility is Euchner-USA

White light color registration sensor

Springfield, O. —Reflex sensor from wenglor Sensors is said to be the first white light sensor for color detection. The white light does not blend with the color to be sensed enhancing setup. The sensor can detect dark green on light green background, white markings on yellow, and a white stripe between yellow and black stripes. wenglor Sensors Ltd.