Digital Pressure Sensor is particularly suitable for use in computer control systems.

SI-520 Digital Pressure Sensor

Digital pressure sensors measure the relative pressure of hydraulic and pneumatic systems. Pressure transmitters provide absolute or differential analog readings over a wide measurement range. SI-520 Digital Pressure Sensor passes high-reliability digital circuit 485 and precision temperature compensation. RS485 half-duplex working mode. This protocol complies with the MODBUS communication protocol. And uses a subset of RMOD methods in the MODBUS protocol. Digital Pressure Sensor adopts 304ss seal and welding, and has compact structure. Digital Pressure Sensor has good moisture resistance and excellent media compatibility.

Sino-Inst offers a variety of low pressure transducers for industrial pressure measurement. If you have any questions, please contact our sales engineers.

Such sensors are also commonly referred to as:
RS485 pressure transmitter. MODBUS protocol transmitter. RS485 bus sensor. Digital signal pressure transmitter.

Measurement medium: weakly corrosive liquid; weakly corrosive gas.

Digital Pressure Sensor Features

Oem smart Pressure Transducer pressure sensor5
  • RS485 communication interface or HART communication protocol (optional)
  • Using digital compensation and non-linear correction technology
  • -10 ℃ ~ 70 ℃ digital wide temperature compensation
  • Support networking application
  • Digital display (optional)
  • Special requirements can be customized to suit various occasions

Extended reading: Pressure indicator transmitters

Specifications of SI-520 Digital Pressure Sensor

Amount-0.1~0,0-1,6,10~100MPaAmbient temperature-20~85℃
Supply voltage24VDC(10~36VDC)Medium temperature-20~85~105℃-500
output signalRS485 half duplexResponse time<1ms
ProtocolMODBUS protocolElectrical InterfaceStainless steel waterproof sealed terminal
Precision0.1%FS、 0.25%FS、0.5%FSThreaded connectionM20 * 1.5 or according to customer requirements
Sampling rate:10 times / second.Overload capacity150%
Communication speed9600bps,n,8,1Sealing levelIP65/68
Communication speed9600bps,n,8,1Stability:≤ ± 0.15% FS / year
Serial port settingsNo parity, 8-bit data, 1 stop bit.
Serial baud rate200,240,048,009,600,000,000,000,000,000,000,000
Vibration effect≤ ± 0.15% FS / year (mechanical vibration frequency: 20Hz ~ 1000Hz)

SI-520 Digital Pressure Sensor Dimensions

SI-520 Digital Pressure Sensor Dimensions

Digital Pressure Sensor Applicaitons

  • Various liquids, gases, or vapors compatible with 304, 316L stainless steel
  • Static & dynamic pressure measurement
  • Vacuum measurement/control
  • Barometric pressure measurement
  • Fluid level measurement
  • Gas Flow
  • Medical Instrumentation
  • HVAC

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What does 485 communication (modbus protocol) mean in a pressure transmitter?

The pressure transmitter has a common 4-20mA output and has Hart protocol. There is also 485 communication which is the modbus protocol. Today we will talk about what is 485 communication.

MCU pin outputs TTL level. TTL level means when the MCU pin outputs 0 level. In general, the voltage is 0V. When the MCU pin outputs 1 level, the voltage is 5V. Because the TTL level is generated by a signal line and a ground line. The interference signal on the signal line will be transmitted to the receiving end with the effective signal, so that the effective signal is interfered. 485 communication actually converts the TTL level from the MCU through a converter chip in the hardware layer.


485 communication features:

  1. RS-485 electrical characteristics:
    Logic “1” is represented by the voltage difference between the two lines being + (2-6) V. Logic “0” is represented by the voltage difference between the two lines being-(2-6) V. The interface signal level is lower than that of RS-232-C, so it is not easy to damage the chip of the interface circuit. And this level is compatible with TTL level, which can be easily connected to TTL circuits.
  2. The maximum data transmission rate of RS-485 is 10Mbps.
  3. The RS-485 interface is strong, which means it has good anti-noise interference.
  4. The standard value of the maximum transmission distance of the RS-485 interface is 4000 feet, in fact it can reach 3000 meters (theoretical data, in actual operation, the limit distance is only about 1200 meters). In addition, the RS-232-C interface allows only one transceiver to be connected on the bus, that is, a single station capability. The RS-485 interface allows up to 128 transceivers on the bus. That is to say, it has multi-station capability, so that users can easily set up a device network using a single RS-485 interface.

RS485 disadvantages:

RS485 bus is a conventional communication bus. It cannot do automatic arbitration of the bus. That is, data cannot be sent simultaneously to avoid bus contention. Therefore, the communication efficiency of the entire system is necessarily low, and the amount of data redundancy is large. RS485 bus is not suitable for application places with high speed requirements. At the same time, because there is usually only one host on the RS485 bus, this bus method is a typical centralized-decentralized control system. Once the host fails, the communication of the entire system is limited to a paralyzed state. Therefore, it is an important measure to do online backup of the host.

Technical Support


How does a digital pressure sensor work?

The working principle of the digital pressure sensor is that the pressure directly acts on the diaphragm of the sensor. The diaphragm generates a micro-displacement that is proportional to the pressure of the medium. The resistance of the sensor changes. This change is detected by electronic circuits. The output is converted to correspond to this Digital standard signal of pressure.
More about: How does a pressure transmitter work?

What does a pressure sensor do?

A pressure sensor is a device or device that can sense a pressure signal. And convert the pressure signal into a usable output electrical signal according to a certain rule.
A pressure sensor usually consists of a pressure-sensitive element and a signal processing unit. According to different test pressure types, pressure sensors can be divided into gauge pressure sensors, differential pressure sensors and absolute pressure sensors.
More: Industrial Pressure Sensors

What is a gauge pressure sensor?

gauge pressure (GP) transmitter, compares a process pressure against local ambient air pressure.
Gauge pressure transmitters have ports to sample the ambient air pressure in real-time.
Today’s highly accurate gauge pressure transmitters can be affected by fluctuations in the local ambient pressure.
Measurements above the ambient air pressure are represented, as a positive number, while a negative number represents measurements below ambient.
A gauge pressure measurement is indicated by the letter ‘g’ following the unit of measure of the reading (i.e., inH₂O(g) or psig).
More: Gauge Pressure Transmitter

How do you test a pressure sensor?

Pressure sensor is a commonly used pressure instrument, which has certain applications in many industries. It is very important for the user to determine how to detect the pressure sensor when using the pressure sensor. According to the purpose of detecting the pressure sensor, the detection items are different, of course, the detection methods will be different. Today, I will mainly introduce the three detection methods commonly used by pressure sensors. I hope they can help everyone.
Pressurization test. The checklist method is to supply power to the sensor. Blow the air holes of the pressure sensor with your mouth. Use the voltage range of the multimeter to detect the voltage change at the output of the sensor. If the relative sensitivity of the pressure sensor is large, this amount of change will be significant. If nothing has changed, you need to use a pneumatic source instead.
Through the above methods, the condition of a sensor can be basically detected. If you need accurate detection, you need to use a standard pressure source to pressure the sensor. Calibrate the sensor according to the pressure and the amount of change in the output signal. When conditions permit, temperature detection of relevant parameters is performed.
Detection of zero point. Use the voltage range of the multimeter to detect the zero point output of the sensor when no pressure is applied. This output is generally a mV level voltage. If it exceeds the sensor’s technical indicators, it means that the zero deviation of the sensor is out of range.
The detection of the bridge circuit. The main test circuit of the sensor is correct. Generally, it is a Wheatstone full bridge circuit. The ohm range of the multimeter is used. The impedance between the input terminal and the impedance between the output terminal. These two impedances It is the input and output impedance of the pressure sensor. If the impedance is infinite, the bridge is disconnected, indicating that there is a problem with the sensor or that the pin definition is not judged correctly.

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