CWT-DPS Differential Pressure Sensor

Introduction:

The differential pressure sensor adopts MEMS pressure sensor and dedicated conditioning chip. It utilizes advanced pressure sensor technology, as well as high-integration, low-power consumption, and high-precision digital processing technology, providing complete pressure calibration and temperature compensation. The product features a 485-communication interface with standard Modbus-RTU communication protocol, supporting a maximum communication distance of 2000 meters. It can seamlessly connect to on-site PLC, configuration software, configuration screens, and industrial controllers. It can also be integrated with our company's supporting network-type concentrator, where the monitoring host uploads data to our free monitoring cloud platform. Real-time data, historical data, alarm records, etc., can be viewed via browsers or mobile APPs. The differential pressure sensor is capable of detecting differential pressure and gauge pressure, widely applied in pressure measurement for medical environments, clean rooms, boilers, dust collectors, vacuum cleaners, power plants, air conditioners, and other scenarios.

Features

• Wide measurement range coverage, optional from -10kPa to 10kPa.
• Aluminum alloy housing with IP54 protection rating.
• Reverse polarity protection and instantaneous overcurrent/overvoltage protection, compliant with EMI protection requirements.
• Pressure overpressure protection, capable of withstanding 2.5 times overpressure instantaneously.
• Automatic temperature compensation with self-correction for temperature drift.
• 485 communication interfaces with standard Modbus-RTU communication protocol.

Specifications

power supply	10-30V DC
Max power consumption	0.3W
Measurement range	-10kPa~10kPa
Accuracy	±1%FS
Operating temperature	-40℃~+60℃, 0%RH to 95%RH (non-condensing)
Output	RS485
Compensation Temperature	-5℃~65℃
Long-term stability	+0.2%FS

Size and installation

 

 

The left interface is the high-pressure port, and the right interface is the low-pressure port. For example, when measuring the pressure difference between two locations, connect the two lower interfaces of the device to the two locations respectively. When measuring the pressure difference between indoor and outdoor areas, introduce the high-pressure port to the indoor space and the low-pressure port to the outdoor space.

 

Wiring

Cable color	Description
Brown	Power + (DC10-30V)
Black	Power -
Yellow	RS485+
Blue	RS485-

RS485 communication

Default parameters: 4800,n,8,1

Default device address is 1

Modbus RTU protocol

Read status registers, read function code: 0x03
Register address (Hex)	PLC Address (decimal)	Meaning	Number of bytes	Content	Remark
0000	40001	Differential pressure value	4		Read (Float 32)
0002	40003	Pressure unit	2	0: Pa (default) 1: kPa 2: MPa 3: Bar 4: mmHg 5: kg/cm² 6: psi 7: mH₂O 8: mmH₂O	Read/Write
0021H	40034	High byte of alarm upper limit	2		Read/Write
0022H	40035	Low byte of alarm upper limit	2		Read/Write
0023H	40036	High byte of alarm lower limit	2		Read/Write
0024H	40037	Low byte of alarm lower limit	2		Read/Write
0025H	40038	High byte of calibration value	2		Read/Write
0026H	40039	Low byte of calibration value	2		Read/Write
0028H	40041	High byte of range upper limit	2		Read/Write
0029H	40042	Low byte of range upper limit	2		Read/Write
002AH	40043	High byte of range lower limit	2		Read/Write
002BH	40044	Low byte of range lower limit	2		Read/Write
Parameters registers, read function code: 0x03, write function code: 0x06
07D0	42001	Slave ID	2		1–254
07D1	42002	Baud rate	2		0: 2400 1: 4800 (default) 2: 9600 3: 19200 4: 38400 5: 57600 6: 115200 7: 1200

E.g., master read Differential pressure value:

Address Code	Function Code	Start Address (Hi)	Start Address (Lo)	Number of Points (Hi)	Number of Points (Lo)	Error Check (Lo)	Error Check (Hi)
0x01	0x03	0x00	0x00	0x00	0x02	0xC4	0x0B

Sensor responds:

Address Code	Function Code	Number of byte	Velocity value	Error Check (Lo)	Error Check (Hi)
0x01	0x03	0x04	0x42 0xC8 0x00 0x00	0xF8	0x6D

Differential pressure value calculates:

42C80000 H=100 => 100Pa

Set slave ID

E.g., set slave ID=2, Master sends

Address Code	Function Code	Start Address (Hi)	Start Address (Lo)	ID	Error Check (Lo)	Error Check (Hi)
0x01	0x06	0x07	0xD0	0x00 0x02	0x08	0x86

Sensor responds:

Address Code	Function Code	Start Address (Hi)	Start Address (Lo)	ID	Error Check (Lo)	Error Check (Hi)
0x01	0x06	0x07	0xD0	0x00 0x02	0x08	0x86

Set baud rate

E.g., set baud rate=9600, Master sends

Address Code	Function Code	Start Address (Hi)	Start Address (Lo)	command	Error Check (Lo)	Error Check (Hi)
0x01	0x06	0x07	0xD1	0x00 0x02	0x59	0x46

Sensor responds:

Address Code	Function Code	Start Address (Hi)	Start Address (Lo)	command	Error Check (Lo)	Error Check (Hi)
0x01	0x06	0x07	0xD1	0x00 0x02	0x59	0x46

Enquiry slave ID

Master sends

Address Code	Function Code	Start Address (Hi)	Start Address (Lo)	Number of Points (Hi)	Number of Points (Lo)	Error Check (Lo)	Error Check (Hi)
0xFF	0x03	0x07	0xD0	0x00	0x00	0x01	0x91	0x59

Sensor responds:

Address Code	Function Code	Number of Points	Address	Error Check (Lo)	Error Check (Hi)
0xFF	0x03	0x02	0x00 0x01	0x50	0x50