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Advantages and Applications of Wireless Load Cells

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The ability to transmit data wirelessly has become standard in most modern technology applications. Companies are opting out of landlines, Ethernet cables, and local servers in favor of wireless and remote options. As the reliability and speed of connections improve, many industries are seeing wireless technology incorporated into everyday tasks. Load cell applications are no exception. This article introduces these wireless load cell scenarios and outlines the advantages of wireless load cells. It concludes with a brief description and comparison of the wireless solutions Tacuna Systems provides.

Where to Go Wireless

The best answer to the question, “where could I incorporate wireless load-cells?” is anywhere that has conventional wired load cells. However, there are places where wired load cells are completely impractical. Wired load cell connections can be challenging, if not impossible, in environments that span large areas, have moving parts or are hazardous to humans.

In these cases, products like the wireless readout in Figure 1 make measurements far more accessible. Where moving parts are involved, operators can receive measurement data at a safe distance. Likewise, fixtures with tight clearances may cause damage to wires and cables; here wireless communication between the load cell and this readout can prevent fires or measurement errors from exposed wires. The good news is that many product options exist to add wireless connections to most load cell applications.

Advantages of Wireless

There are numerous advantages to wireless load cell technology in these industrial environments.

Mobility

Often with large-scale or distributed systems, operators must collect measurement data while maneuvering around distances or large obstructions. Wireless receivers or indicators give the user access to real time data from any such location. This improves the efficiency over a central, wired collection site when calibrating and testing load cells or performing routine maintenance.

photo of wired system with many wires
Figure 2. Complex Wiring Systems

Flexibility of Interfaces

Conveniently, there are smart phone and tablet apps that receive wireless load cell data transmission. These apps not only display the data to operators, but can also further process it. This can streamline procedures and makes operator training easier. Even when wired connections are possible, wireless receivers allow operators to observe multiple load cells from a single workstation. This further simplifies standard work procedures.

Reduced Cost and Complexity: Installation and Maintenance

The most significant expenses with complex load cell or strain gauge measurement systems are from installation and servicing. This is especially true of transmission cabling installation from the sensors to the user interface. Transmission cables and wiring harnesses can be tedious to properly install; improperly installed cables can become a safety risk by entangling equipment or personnel. These expenses further multiply where wiring must be underground or aerial (much like telephone transmission cables) for protection from environmental hazards. Also, long wiring runs degrade signals and require more equipment to compensate for this.

Obviously, wireless load cell signal transmission eliminates the need for these wire runs. The initial installation of wireless transmitters and receivers is clearly more cost-effective in both equipment and labor hours. As mentioned above, wireless systems allow the consolidation of output user interfaces, further decreasing installation complexity and cost.

When it comes to maintenance, wireless systems are also the clear winner. Wireless measuring systems only require access to specific measurement locations or nodes, potentially saving thousands on inspections and upkeep.

Safety

Wireless technology greatly increases safety when installing or maintaining a measuring system in rugged terrain or on moving equipment. This is likewise true even during the system’s normal daily use. Non-wired connections also mitigate risk in flammable environments if wires fray due to wear, as these could ignite hazardous fumes. This contributes to the cost benefit of wireless technology.

Applications of Wireless Load Cells

Distance Applications and Wireless Telemetry

Telemetry, or the transmission of data or signals over long distances, is used to monitor remote, inaccessible locations. Wireless telemetry allows operators to gather accurate measurements in very large or distributed environments.

The advantages to wireless communication are many when a measurement application is at a remote distance. Unlike traditional wiring, wireless telemetry is less impeded by physical barriers. Signals can go through walls, piping, ducts, and most other materials with relatively little interference. Also, as mentioned above, wireless systems only require access to specific measurement locations or nodes. This greatly lowers the complexity of installing and maintaining systems applied over large-scale surfaces or regions of land.

For long-term civil structures such as bridges and buildings, remote monitoring of the structure’s loading can help pinpoint potential damage. In the past, engineers had relied on visual inspections to detect structural damage. However, these visual inspections are only as effective as the inspection frequency and the inspector’s subjective judgment. The use of grids of wireless load cells or strain gauges eliminates much of this human effort and potential error. These grids create a matrix that allows real-time monitoring of large surfaces (see figure below). This in turn leads to earlier and faster detection of strain localization and prediction of structural damage.

Photo of Bridge showing strain gauge placement
Load Cell or Strain Gauge Matrix on a Bridge

One can easily conclude from this that wireless automation reduces inspection costs and risks associated with accessing large structures. Automated, wireless monitoring of structures can ultimately improve the life of the structure, regulate scheduled maintenance, and reduce inspection time.

Dynamic and Moving Systems

When the measured object or system is static, connections to the measuring system are simple. However, if the measured object is mobile or dynamic in nature, monitoring becomes an increasingly complex challenge. Load cell wiring can interfere with the motion of these systems and can be damaged.

Some examples of mobile applications using load cell measurement are cranes, forklift scales, and other hoisting applications. Propellers, wind turbine blades, pumps, rotors, and engines are common applications of fast moving parts.

Propeller With Strain Gauges
Figure 4. Propeller Outfitted with Strain Gauges

Rotating Systems

Any rotating system that requires measurement creates a challenge when measuring.

Slip rings are electromechanical devices that transmit an electrical signal from a rotating system to a fixed system. Rotating objects cannot be restrained by connected wiring so a slip ring is used to transfer both power and data. Slip rings simplify systems and eliminate wired connections that could experience damage during operations.

These devices do require frequent maintenance and struggle with reliability. Because they are subject to constant movement, slip rings need constant upkeep. Without proper maintenance, they can degrade due to contaminants and constant abrasion. Slip rings are difficult to repair and usually require replacement if damaged.

Reliability aside, slip rings are often preferred for high-speed or high-rpm data transmission. Market solutions exist that fully replace rotating gauges and load cells with wireless transmitters; however they become less accurate as speeds increase. This makes them impractical to use on applications like engines. Wireless technology is always improving; however slip rings remain the most feasible solution.

Hoisted Applications

Cranes and other hoists are in constant movement during standard operations. At the same time, there is the need to monitor the loads they bear, for safe operations. Using wireless technology for these applications is especially useful around construction, as the load measuring fixtures are in constant movement.

Two load cell types used for these applications are crane scales and load pin load cells. The section below, “Specific Hoisting Applications,” describes these devices.

Dangerous Environments

Many measurement applications exist that have inherent risk due to their location. For example, mining, oil refineries, furnaces, offshore and on-land oil rigs, and nuclear reactors may incorporate load cells in their monitoring systems. These rely on accurate data. However, their higher than normal radiation, toxic or explosive atmospheric conditions, extreme temperatures, or submersed implementation creates risk to technicians and operators. Eliminating cable runs in these applications reduces installation, inspection, and troubleshooting time. This in turn reduces the duration of a technician’s exposure to these dangerous conditions. That is, while hazards are unavoidable, in these applications, wireless telemetry eliminates failure points and maintenance associated with wired connections.

Internet of Things (IoT)

The Internet of Things is simply a concept – one where all the devices with which we interact connect wirelessly to the internet to improve their efficiency, safety, or user experience. These devices can be consumer in nature or part of a business or manufacturing process. What these devices all have in common is the use of wireless sensors to collect and report desired data. This data is then processed by an application that in turn determines some course of action by a consumer-oriented or manufacturing control system. And, full circle, this system functions to improve efficiency, safety or user experience.

The applications above could be considered part of the Internet of Things. However the IoT is broader than just these. For a more detailed overview of the IoT, see the article, The IoT and Sensors: A Quick Overview.

Implementation of Wireless Load Cells

As described above, wireless load cells can provide many advantages over wired connections. But there is more than one way to implement wireless transmission. The three main ones are:

  • Integrated wireless transmitters internal to load cell devices paired with any receiver,
  • Integrated wireless transmitters internal to load cell devices paired with a dedicated wireless indicator such as the ANYLOAD 805HP-WL in Figure 1, and
  • Wireless bridges that act as the transmitter and receiver between any current or customized measurement system. These devices replace intermediate lengths of wire. This concept is covered in the next section.

Products that Convert Conventional Load Cells to Wireless

Often the easiest way to implement wireless measuring is to outfit existing analog load cells with wireless transmission. This provides minimal up-front investment in new measurement devices. It also upgrades existing systems with minimal impact to the load cell frame or fixture.    

With Tacuna Systems’ TBX Wireless Load Cell Bridge, any standard load cell application can be converted to wireless. The TBX wireless bridge replaces any physical wire or cable connection between load cells and measurement indicators. It easily retrofits to existing systems but it can also be part of new measuring system deployments.  Likewise, our ANYLOAD WL100 and WL900 Transmitter/Receiver products function similarly.

The transmitter on all three products connects directly to the load cell’s output wiring. This converts any load cell, scale, pressure sensor, torque sensor and resistive sensor to wireless.

The receiver device for the TBX transmitter can be one of several configurations. Option one is to pair its transmitter with its receiver connected to a standard weight indicator. The second option is to pair its transmitter with the TBX app on any smartphone or tablet.  Finally, the TBX-T transmitter can pair directly with software on a device (tablet or computer) with compatible reception; this makes storing and displaying data more user-friendly.

The WL100 receiver can collect data from multiple sensors. It connects to a computer via USB that must run the WL100 app to collect and display the load cell data. The WL900 receiver interfaces exclusively with the ANYLOAD 808 series wireless displays discussed below.

Both the TBS and WL100 devices use Bluetooth low energy 2.4 GHz radio connections. The WL900 uses a 900MHz transmission frequency.

Products for Hoisting Applications

As mentioned before, wireless technology is highly advantageous for cranes and other hoists, as they are in constant motion during use.

Tacuna Systems offers the ANYLOAD 110ES-WL wireless crane scale with standard wireless transmitters for measuring crane loads of up to 100 tons.  It is designed to withstand harsh conditions with salt and waterproof stainless steel casting and a silicone-enclosed antenna. It can also be used in other hoisting and lifting applications. Other hoisting products in our shop include the ANYLOAD 110RH-WL Wireless Alloy Steel Tension Link, with capacities up to 50 tons, and the ANYLOAD OCSD Wireless Dynamometer, with capacities of up to 200 tons. Other than range of capacities, these three products differ in their environmental rating; the 110ES-WL is IP68/69, the 110RH-WL is IP67, and the OCSD is not rated. The ANYLOAD 110 series wireless crane scales pair with the  ANYLOAD 805HP-WL Wireless Hand Held Indicator; the OCSD pairs with the ANYLOAD P180 Wireless Display.  

Photo of Crane Weighing Large Objects
Figure 5. Weighing of Large Structures with a Crane

Another wireless hoisting option offered by Tacuna Systems is the ANYLOAD TBX Shackle. This combination shackle/load cell is ideal wherever pinned shackles bear the primary load path.  If a load is borne by a pin, this pin can be replaced by a load pin load cell. For additional information on suspension load cell systems, see the Tension and Suspension Applications section of our article Load Cell Mounting and Installation Best Practices

Wireless Indicators and Displays to Improve Productivity

For many measuring applications, wired connections are still viable. However, even for these, mobile readouts can increase efficiency or improve ease-of-use for operators. In these cases, Tacuna Systems recommends the use of a wireless display or indicator as the output interface.  

For high visibility displays in stationary locations, we offer ANYLOAD’s 808 Series LED wireless load cell indicators. These include the 808AH-WL, 808BH-WL, and 808CH-WL. These come with the WL900 Transmitter/Receiver, to connect to any wired load cell.

Handheld indicators are are simple, single-point, devices that interface with most load cells. Tacuna Systems offers the ANYLOAD 805HP-WL Wireless Hand Held Indicator and the ANYLOAD P180 Wireless Display.  These pair with the wireless crane scales discussed in the last section.

A Comparison of Tacuna Systems Wireless Products

Products that Convert Conventional Load Cells to Wireless

FeatureModels
ANYLOAD WL100ANYLOAD WL900TBX Wireless Bridge
Compatible Withall resistive bridge sensors,
all brands
all weight indicators/brands
(to connect to
ANYLOAD 808 Series displays)
all strain load cells,
all brands
Display TypeSoftware interfaceLEDReceiver connects via load cell
connectors to standard display, or
can display to mobile app
(receiver not needed)
Frequency of Transmission2.4 GHz ISM Band900MHz
(US / CAN / AUS / EU)
Bluetooth 4.0 Low Energy 2.4 GHz
ApprovalsFCC, CE, RCM, R-NZ, TELEC, ANATEL, KCCFCC, IC, C-TickCE, RED, RoHS, MD
Display DigitsNoneSix; 0.4″ (10mm) high, 7-segmentNone
Communication PortsTransmitter: load cell pin connector
Receiver: USB connector to PC
3 independent serial ports:
RS232, RS422/RS485, 20mA current loop
Transmitter: load cell pin connector
Receiver: RS232 for communicating
transmitter battery status
Enclosure MaterialABSStainless SteelMetal enclosure
IP Rating6565Moisture resistant
External Power Supply4 x AA BatteriesInput: 100-240VAC, 0.6A, 50/60Hz /
Output: 12VDC, 2.0A, 25W wall adaptor
Transmitter: 3 x AA battery, Li-Ion / Li-Po 3.7V
Receiver: 5 – 10 VDC supplied by the
connected load cell indicator
Battery Life<7000 hours
 with a 350O bridge and 1Hz sampling rate
100 hoursTransmitter: 1000 hours
Wireless Range70m (indoor);
1000m (unobstructed)
100m (indoor);
300m (unobstructed)
20m
Working Temperature-10°C to 50°C / 14°F to 122°F-40°F to 120°F (-40°C to 50°C)-40°C to 85°C
Dimensions (mm)45 x 30 x 15 (without battery)144 W x 142 H x 44 D86 x 47 x 12 (without housing)
Dimensions (inch)1.8″ x 1.2″ x 0.6″5.7″ W x 5.6″ H x 1.7″ D 3.2″ x 2″ x 0.5″
Total Weight1.0 kg (2 lbs), including wall adaptor

Products for Hoisting Applications

FeatureModels
ANYLOAD 100ES-WLANYLOAD 100ES-WLANYLOAD OCDS
Capacities1t-100t500kg – 50t1t-200t
Accuracy (depending on Capacity)1:3000 to 1:50001:3000 to 1:50001:2000 to 1:3000
Material304 Stainless SteelPowder Coated Alloy Steel1-5t: Aluminum
>10t Alloy Steel
IP RatingIP68/69IP67none given
Receiver OptionsANYLOAD 805HP-WLANYLOAD 805HP-WLANYLOAD P-Series
Transmission Range<30m30-75m (depending on frequency)<30m
Battery Life<8 hour<100 hour (depending on range)<50 hour

Wireless Indicators and Displays to Improve Productivity

FeatureModels
ANYLOAD
805HP-WL
ANYLOAD
P180
ANYLOAD
P380
ANYLOAD
P580
ANYLOAD
808AH-WL
ANYLOAD
808BH-WL
ANYLOAD
808CH-WL
Compatible Withall load cells,
all brands (up to 16
load cells w/Junction Box & Wireless Transmitter)
ANYLOAD OCSD
Dynamometer
ANYLOAD OCSD
Dynamometer
ANYLOAD OCSD
Dynamometer
all load cells,
all brands via WL900
transmitter/receiver (included)
all load cells,
all brands via WL900
transmitter/receiver (included)
all load cells,
all brands via WL900
transmitter/receiver (included)
Display TypeLCDLCDLCDLCD (and Fujitsu
FTP-680 thermal printer)
LED
(with brightness control and 120° viewing angle)
LED
(with brightness control and 120° viewing angle)
LED
(with brightness control and 120° viewing angle)
Display Number of Digits655566 plus semaphore5
Display Digit Height17mm / 0.66in12mm/0.47in25mm/1in25mm/1in125mm/5in125mm/5in62.5mm/2.5in
Display BacklightToggle on-off
(battery saver)
YesYesYesNANANA
Unitskg, g, t, lb, klb,
N, kN, oz
or user-defined
kg/lbkg/lbkg/lb
Enclosure MaterialABSMild steel powder
coated NEMA 4
Mild steel powder
coated NEMA 4
Mild steel powder
coated NEMA 4
IP Rating65656565
Power Source3 x AA Alkaline batteriesUSB connection
or rechargeable lithium battery (included)
4 x AA (rechargeable)Ni-H batteryInput: 100-240VAC, 1.2A, 50/60Hz
Output: 12VDC, 5.0A, 60W encapsulated
Input: 100-240VAC, 1.2A, 50/60Hz
Output: 12VDC, 5.0A, 60W encapsulated
Input: 100-240VAC, 1.2A, 50/60Hz
Output: 12VDC, 5.0A, 60W encapsulated
Battery Life<100 hours50 hours50 hours50 hoursNANANA
Frequency900MHz2.4GHz (two-way)2.4GHz (two-way)2.4GHz (two-way)(per WL900)(per WL900)(per WL900)
Wireless Range75m
unobstructed
30m30m30m(per WL900)(per WL900)(per WL900)
ConnectivityUSB port to PCRS232 to printer; other peripheralsUSB and
RS232
3 serial ports for RS232, RS422/RS485, &
20mA current loop
(auto-learn baud rate & protocol) and
RF Wireless link (both transmit and receive)
3 serial ports for RS232, RS422/RS485, &
20mA current loop
(auto-learn baud rate & protocol) and
RF Wireless link (both transmit and receive)
3 serial ports for RS232, RS422/RS485, &
20mA current loop
(auto-learn baud rate & protocol) and
RF Wireless link (both transmit and receive)
Working Temp-20° to 70° C
-4° to 158°
-20°C to 60°C
-4°F to 140°F
-20°C to 60°C
-4°F to 140°F
-20°C to 60°C
-4°F to 140°F
-40°F to 120°F
-40°C to 50°C
-40°F to 120°F
-40°C to 50°C
-40°F to 120°F
-40°C to 50°C
Dimensions (mm)170 x 98 x 3428 x 70 x 90220 x 105 x 50
(handheld)
220 x 130 x 92658 x 348 x 149918 X 348 X 149353 x 191 x 116.8
Dimensions (in)6.7 x 3.9 x 1.341.10 x 2.8 x 3.548.7 x 4.1 x 28.7 x 5.1 x 3.625.9 W x 13.7 H x 5.9 D36.1 W x 13.7 H x 5.9 D13.90 x 7.52 x 4.60

Conclusion

With the rise in cloud computing, internet incorporation, and big data analysis, wireless systems are increasingly critical to business innovation. As the reliability and speed of wireless technology improves, companies will continue to swap physical connections for digital and wireless.

Wireless transmission of data in load cell measurements likewise continues to improve. For example, wireless technology solutions now exist for most load cell applications. Moreover this technology has many advantages including allowing operators to gather accurate, real-time measurements in distant, dynamic or dangerous environments. It reduces the management of cabling for weighing applications on moving systems like wind turbines, in fixtures with tight tolerances where wires could become damaged, or in inaccessible environments. Operators also have increased mobility and maneuverability, which improves their speed and job efficiency. Utilizing wireless load cells can ultimately improve safety for operators and technicians, and reduce the cost of installation and maintenance.

References

  • Measurement and Instrumentation: Theory and Application, Alan S Morris, Reza Langari 
  • Measurement and Instrumentation in Engineering: Principles and Basic Laboratory Experiments,1st Edition, Francis S. Tse, Ivan E. Morse
  • Civil Structure Strain Monitoring with Power-Efficient,High-Speed Wireless Sensor Networks”, J.H. Galbreath, C.P. Townsend, S.W. Mundell, M.J. Hamel
  • B. Esser, D. Huston, Ph.D., S.W. Arms, 4th Int’l Workshop on Structural Health Monitoring Stanford University, Stanford CA, Sep, 2003
  • Large-Scale Surface Strain Gauge for Health Monitoring of Civil Structures, Simon Laflamme, Matthais Kollosche, Guggi Kofod, Smart Structures and Materials, 2012
  • Douglas DC-3 Re-engine STC Project
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