Advantages of Digital Pressure Sensors

Pressure sensors are used in a variety of industrial applications ranging from hydraulics and pneumatics; water management, mobile hydraulics and off-road vehicles; pumps and compressors; air conditioning and refrigeration systems to plant engineering and automation. They play a key role in ensuring that system stress is within acceptable limits and help ensure reliable operation of applications. Depending on the installation and system requirements, there are different advantages to using analog and digital pressure sensors.

When to Use Digital and Analog Pressure Sensors in System Design

If the existing system is based on analog control, one of the advantages of using an analog pressure sensor is its simplicity of setup. If only one signal is needed to measure a dynamic process in the field, an analog sensor combined with an analog-to-digital (ADC) converter would be a simpler solution, whereas a digital pressure sensor would require a specific protocol to establish communication with the sensor.If the system electronics require a very fast active feedback control loop, a pure analog pressure sensor is the best solution. For systems that do not require response times faster than about 0.5ms, digital pressure sensors should be considered, as they simplify networking with multiple digital devices and make the system more future-proof.

An opportune time to consider switching to digital pressure sensors in an analog system is to upgrade components to include programmable microchips. Modern microchips are now cheaper and easier to program, and their integration into components such as pressure sensors could simplify maintenance and system upgrades. This saves potential hardware costs, as the digital sensor can be updated via software rather than replacing the entire component.

An opportune time to consider switching to digital pressure sensors in an analog system is to upgrade components to include programmable microchips. Modern microchips are now cheaper and easier to program, and their integration into components such as pressure sensors could simplify maintenance and system upgrades. This saves potential hardware costs, as the digital sensor can be updated via software rather than replacing the entire component.

The plug-and-play design and shorter cable length of the digital pressure sensor simplifies system setup and reduces overall installation cost for applications set up for digital communications. When the digital pressure sensor is combined with a GPS tracker, it can remotely locate and monitor cloud-based remote systems in real-time.

Digital pressure sensors offer many advantages such as low power consumption, minimal electrical noise, sensor diagnostics, and remote monitoring.

Advantages of Digital Pressure Sensors

Once a user has evaluated whether an analog or digital pressure sensor is best for a given application, understanding some of the beneficial features digital pressure sensors offer for industrial applications will help improve system safety, efficiency, and reliability.

A Simple Comparison of Inter-Integrated Circuit (I 2 C) and Serial Peripheral Interface (SPI)

Two digital communication protocols commonly used in industrial applications are Inter-Integrated Circuit (I 2 C) and Serial Peripheral Interface (SPI). I2C is better suited for more complex networks because fewer wires are required for installation. Also, I2C allows multiple master/slave networks, while SPI only allows one master/multiple slave network. SPI is an ideal solution for simpler networking and higher speeds and data transfers such as reading or writing SD cards or recording images.

Output signal and sensor diagnostics

An important difference between analog and digital pressure sensors is that analog provides only one output signal, while digital sensors provide two or more, such as pressure and temperature signals and sensor diagnostics. For example, in a gas cylinder measurement application, the additional temperature information expands the pressure signal into a more comprehensive measurement, allowing the gas volume to be calculated.Digital sensors also provide diagnostic data, including critical information such as signal reliability, signal readiness, and real-time faults, enabling preventive maintenance and reducing potential downtime.

Diagnostic data provides a detailed status of the sensor, such as whether the sensor element is damaged, whether the supply voltage is correct, or whether there are updated values in the sensor that can be obtained. Diagnostic data from digital sensors can lead to better decisions when troubleshooting than analog sensors that do not provide detailed information about signal errors.

Another benefit of digital pressure sensors is that they have features such as alarms that can alert operators to conditions outside of set parameters and the ability to control the timing and interval of readings, helping to reduce overall energy consumption. Because the digital pressure sensor provides a large number of outputs and diagnostic functions, the overall system is more powerful and efficient, because the data provides customers with a more comprehensive evaluation of the operation of the system. In addition to expanding measurement and self-diagnostic capabilities, the use of digital pressure sensors can also accelerate the development and implementation of Industrial Internet of Things (IIoT) systems and big data applications.

environmental noise

Electromagnetically noisy environments near motors, long cables, or wireless power sources can create signal interference challenges for components such as pressure sensors. To prevent electromagnetic interference (EMI) in analog pressure sensors, the design needs to include proper signal conditioning such as

Grounded metal shields or additional passive electronic components, as electrical noise may cause false signal readings. All analog outputs are extremely susceptible to EMI; however, using a 4-20mA analog output can help avoid this interference.

In contrast, digital pressure sensors are less susceptible to environmental noise than their analog equivalents, so they make a good choice for applications that need to be aware of EMI and require an output other than a 4-20mA solution. It should be noted that different types of digital pressure sensors offer different degrees of EMI robustness, depending on the application.Inter-Integrated Circuit (I2C) and Serial Peripheral Interface (SPI) digital protocols are well suited for short-reach or compact systems with cable lengths of less than 5m, although the exact allowable lengths are largely dependent on the type of cable and pullwire. on the resistor. For systems requiring longer cables up to 30m, CANopen (with optional shielding) or IO-Link digital pressure sensors would be the best choice for EMI immunity, although they require more than I2C and Serial Peripheral Interface (SPI ) high power consumption) counterparts.

Data Protection Using Cyclic Redundancy Check (CRC)

Digital sensors offer the option to include a CRC in the chip to help ensure that customers can rely on the signal. The CRC of the communication data is a supplement to the integrity check of the internal chip memory, allowing the user to 100% verify the sensor output, providing additional data protection measures for the sensor.The CRC function is ideal for pressure sensor applications in noisy environments, such as those installed near transmitters in cloud-based systems. In this case, there is an increased risk of noise disturbing the sensor chip and generating bit flips that could alter the communication message. A CRC on memory integrity will protect the internal memory from such corruption and repair it if necessary.Likewise, some digital sensors also provide an additional CRC in the data communication, indicating that the data transmitted between the sensor and controller has been corrupted and may trigger another attempt to evaluate a correct sensor reading.In some cases, end users circumvent this by interweaving communication with the sensor with external communication, such as with the cloud, gateway, or controller. The CRC simplifies this process and provides greater flexibility to the designer. In addition to data validity checks, some manufacturers have added more electronics to suppress noise from sources such as WiFi, Bluetooth, GSM, and ISM bands to further protect data validity.

Digital pressure sensor at work supports smart water distribution networks

Water loss due to leaks, inaccurate metering, unauthorized consumption or a combination of the three is a constant challenge for large water distribution networks. Applying low-power digital pressure sensors to nodes throughout the water distribution network is a practical and cost-effective way to map a regional water distribution network and allow utilities to detect and locate areas where unexpected water loss occurs.

When applied to the nodes of the entire water distribution network, digital pressure sensors can help identify unexpected water loss areas, thereby effectively troubleshooting and improving system efficiency.

Pressure sensors well suited for these applications are typically either hermetically sealed to IP69K or modular to give customers greater design flexibility. To prevent water from penetrating the sensor throughout the life of the application, some pressure sensor manufacturers use a glass-to-metal hermetic connection. The glass-to-metal seal is watertight and creates an airtight seal on the “top” of the sensor, which helps the sensor achieve IP69K. This sealing means that the sensor is always measuring the pressure difference between the substance in the application and the air around it, preventing offset drift.

Improved pressurized gas system regulation

Pressure sensors play a variety of important roles in the monitoring and delivery of pressurized air and medical gases throughout distribution networks. In these types of applications, pressure sensors can be responsible for compressor control and various monitoring functions, including intake and output flow, cylinder exhaust, and air filter status.While a single pressure signal can indirectly measure the amount of gas particles at a location in the system, the combination of pressure and temperature feedback provided by a digital pressure sensor can provide a better estimate of the amount of gas at that location, allowing for better system tuning and monitoring. This allows system developers to get closer to the ideal operating conditions for the application.

While there are still some installations that are best suited to use analog pressure sensors, more and more Industry 4.0 applications benefit from using their digital counterparts. From EMI immunity and scalable networking to sensor diagnostics and data protection, digital pressure sensors enable remote monitoring and predictive maintenance, improving system efficiency and reliability. A robust sensor design with specifications such as an IP69K rating, additional data integrity checks, and extensive onboard electronics for EMI protection will help increase lifetime and reduce potential signal errors.