Smart Force Sensors

The IO-Link amplifier module offers numerous functions that enhance the precision of your force measurements through linearisation and digital temperature compensation, while also improving process reliability via HBK sensor health monitoring. Additional information, such as temperature data, is also provided.

• Linearisation
• Adjustable low-pass filter
•  Two limit switches
• Two digital switching outputs
• Sensor Health Monitoring
• Statistical functions (Min/Max memory, average values)
• Temperature Information

Linearisation

You can enter up to 21 supporting points. Alternatively, you can use the coefficients of a polynomial interpolation of the sensor’s characteristic curve. Both algorithms are designed for optimal use of calibration certificates.

Hint: HBK will enter the parameters from the calibration certificate if you order the calibration of your sensors through HBK. In this case, your sensor will be returned as a plug-and-measure transducer!

Adjustable low-pass filter

Digital 6th-order filters (Bessel or Butterworth) with freely adjustable cut-off frequency

Two limit switches

The limit switches are designed in accordance with the IO-Link “Smart Sensor Profile.” In addition to the switching level, you can define a hysteresis if required. The so-called “Window Mode” allows you to activate the limit switch when the measured value falls within a defined force range, for example, between 1 kN and 1.8 kN. All switches can be negated.

Two digital switching outputs

One output switch is always available. The result is provided very quickly at the digital switching output – with a maximum latency of just 0.35 ms after the switching point is exceeded.

You can stop the IO-Link communication to deactivate measurement data transmission. In this case, the line normally used for digital signal transmission can be repurposed as a second digital output switch.

Sensor Health Monitoring

The sensor issues a warning when physical limits are exceeded – such as static or dynamic overloads, or temperatures beyond specification.

The relevant sensor characteristics are stored in the sensor memory:

• Highest and lowest operational temperature
• Highest and lowest nominal temperature
• Amplifier module temperature limit
• CPU temperature limit
• Highest and lowest nominal force
• Highest and lowest operational force
• Maximum peak-to-peak-to-peak force

The amplifier module continuously compares the measured values with the defined limits and sends a warning in case of a transgression, allowing corrective action to be taken. The high sampling rate of 40 kS/s ensures that even short overload peaks are detected and trigger a warning

• Statistical functions (Min/Max memory, average values)

All statistical functions are evaluated at a sampling rate of 40 kS/s. This ensures accurate Min/Max values, even in the case of fast force signals.

• Temperature Information (when the amplifier module is integrated into the sensor: U10M, U10F, C10, U2B, C2)

An important feature is the integrated temperature measurement within the sensor. This provides your process temperature without the need for an additional temperature sensor. This feature is not available for sensors using an inline amplifier.

HBK force transducers with IO-Link operate at an internal sampling rate of 40 kHz and support the COM3 standard, which offers the fastest data rate in the IO-Link ecosystem. The cycling time of our sensors is less than 1 ms. The cycling time of your setup depends on the IO-Link master and its configuration.

HBK uses the COM3 standard, which provides the fastest data rate in the IO-Link ecosystem. The module operates internally at a high sampling rate of 40 kHz, ensuring that peak detection works accurately even with fast force signals.

Two aspects are important:

1. The signal propagation time of the amplifier module is no more than 350 µs. This means it takes a maximum of 0.35 ms for a physical event at the input of the amplifier to become available at its output. The IO-Link interface operates on the principle that the IO-Link master determines the cycle time. The maximum propagation delay is the sum of the amplifier module’s internal delay (0.35 ms) and the cycle time specified by the IO-Link master through its parameterisation and technical characteristics. Please note that filters increase the signal propagation time. The output to the digital switching outputs does not depend on the IO-Link master – the signal propagation delay in this case is 0.35 ms. These sensors support fast switching.
2. The bandwidth of the measurement chain depends on the stiffness of the sensor and the mechanical installation – such as the stiffness of the load introduction and the weight of the adapted components – from a mechanical perspective. The number of measurement values transmitted per second is the key factor in calculating the bandwidth of any digital measurement chain. The amplifier module has a cycling time of less than 1 ms, which means it can transfer more than 1,000 measurement values per second. As a rule of thumb, the bandwidth is approximately one-tenth of the number of transmitted measurement values per second. If the IO-Link master also has a cycling time of 1 ms, the resulting bandwidth is 100 Hz – assuming the mechanical installation supports measurement at that frequency.

Please note that the internal bandwidth is 40 kHz – peak detection is capable of measuring much faster.

IO-Link is an outstanding, cost-effective interface that is compatible with any fieldbus system. It enables a time-saving integration process and can be used in combination with low cabling costs. Easy and fast integration of IO-Link devices into your fieldbus environment is another major advantage of this interface.

The gateway that links IO-Link devices – such as HBK sensors – to the fieldbus level is the so-called IO-Link master. IO-Link masters are available for all existing fieldbus systems, which means IO-Link sensors and actuators can be used across all fieldbus platforms.

The connection between the sensor and the IO-Link master uses an unshielded M12 standard sensor cable. This single cable handles both data transmission and voltage supply and is highly flexible – ensuring it does not affect the mechanical properties of the measurement point, even when sensors for very small forces are used.

As mentioned above, IO-Link connection cables have no shielding, and both the sensor and the housing of the IO-Link master are galvanically insulated. In case of differing electrical potentials between the sensor housing and the IO-Link master housing, no current flows over any shielding that could influence the measurement.

Yes. For the new generation of force measurement tools, HBK offers the same calibration service as for traditional products, ensuring traceable measurements. The requirements of quality standards such as ISO 9001 can be fulfilled without restrictions.

The HBK calibration laboratory is certified in accordance with the ISO 17025 standard. This means that HBK’s calibration services meet all requirements for traceability to national standards – a key requirement of quality standards like ISO 9001. The calibration process for digital sensors is identical to that of traditional load cells: the same calibration rigs and standards are used. As a result, customers benefit from the high accuracy of HBK’s calibration equipment for digital sensors.

The calibration procedure is as follows:

a. The first step is to read out all data for linearisation (supporting points or coefficients of the cubic polynomial) stored in the sensor. This data is safely stored externally.
b. After this, all linearisation data is deleted. The sensor now operates without correction for linearity error.
c. Different load steps are applied to the sensor, and the results are stored in the sensor memory. The sensor now operates with linearity correction.

As a result, you receive a plug-and-play sensor with active compensation for linearisation error. The measurement uncertainty calculation is valid for the complete system.

Working standard calibration service is also available.

Cost savings, easy and fast setup, and communication down to the field level – the advantages are substantial.

In most cases, cost savings are the strongest argument for choosing a sensor with IO-Link technology. The most important benefits of IO-Link technology include:

1. No space required in the cabinet.
2. Lower cabling costs.
3. Time savings during the integration process.
4. Plug and play without parameterisation: after connecting the device to an IO-Link master, you immediately receive accurate measurement values in Newtons.
5. Communication from the control level to the field level is possible.

The improved accuracy helps you meet increasingly demanding product quality requirements. In addition, IO-Link force sensors from HBK are even more reliable than HBK’s already well-known products.

Smart force transducers from HBK improve accuracy.

The linearisation algorithms of the sensors improve the accuracy of the digital sensors – especially when a calibration is ordered. Sensors with an integrated amplifier module (U10M, U10F, C10, U2B, C2) also feature digital temperature compensation. The effect of temperature on the zero point – one of the most important factors contributing to force measurement uncertainty – is reduced to just half that of passive versions. Since no cable transmits analogue signals, the influence of electromagnetic fields is minimised. HBK uses a low-noise amplifier module with high resolution.

Smart force sensors are highly precise measurement tools. Especially in industrial environments with challenging temperature conditions and a wide measurement range, they offer excellent accuracy.

The mechanical robustness of the sensor remains unchanged with the integrated amplifier. The temperature range is lower than that of traditional sensors – please refer to our datasheets.

HBK performs shock and vibration tests on every product. When it comes to the integrated electronics, there are no compromises: resistance to shock and vibration is equivalent to that of traditional sensors and is tested in accordance with the relevant IEC standards. The same applies to the degree of protection. The inline amplifier achieves protection class IP67, as do the force transducers with integrated amplifiers. Please note that a suitable cable must be connected to the sensor to maintain this level of protection.

Regarding temperature, the sensors are limited by the characteristics of the electronic components. The temperature range is restricted to 60°C, compared to 85°C for traditional versions.