ASAIR AFM0725 User manual

The AFM0725 is a thermal mass flow sensor that calculates the mass flow of the gas being measured by measuring the change in resistance. The sensor adopts
the self-developed MEMS mass flow chip, which has the characteristics of intuitive, accurate, stable, high and low temperature resistance, good linearity, and short response
time.
AFM0725 is suitable for mass flow monitoring of air, nitrogen, argon, carbon dioxide, helium, oxygen and other dry, clean and non-corrosive gases (except flammable
and explosive gases). It has been widely used in university scientific research, fire protection, environmental monitoring, tobacco, smart agriculture, food, medicine and other
industries.
The range, accuracy, repeatability and response time of AFM0725 have been strictly calibrated before leaving the factory.
ÿ Integrated mass flow and temperature
measurement ÿ Good repeatability ÿ Supports
multiple gas measurements ÿ Standard Modbus-
RTU communication ÿ 2 NPN open collector
outputs (for upper and lower limit alarms) ÿ 1~5V linear voltage output 9ÿ24V DC power
supply
AFM0725 Instruction Manual
1 /
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Figure 1.
July 2022
AFM0725
Product description
Gas Mass Flow Meter
Scope of application

Figure 2 shows the appearance structure and working interface of AFM0725, including the sensor air duct and working interface. The working interface includes an LCD
display screen and operation buttons. The contents displayed on the LCD include the Modbus communication address of the flowmeter, gas temperature, cumulative flow and
instantaneous flow. The buttons include up, down and set buttons, and the LCD lights 1 and 2 are the upper limit warning light and the lower limit warning light respectively. The
sensor air duct is below the working interface, including the air inlet and the air outlet.
1. Appearance structure and interface definition
2 of
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Figure 2. AFM0725 Block
July 2022
Diagram
1.1 Appearance structure

2
power cable
GND
grey line
white line
Voltage outputyellow line
8
Table 1. Device 8Pin female header pin definition
External output 2
Voltage output
External output 1
GND
6
pinout
4
1
definition
orange line
definition
red line
GND
External output 2
black line
External output 1
Figure 3. Schematic diagram of device 8Pin female socket
RS485B
RS485A
power cable
GND
5
green line
RS485A
7
pin
3
Table 2. Pinout Definitions
brown wire
RS485B
1.2 Device 8Pin female socket
1.3 AFM0725 pinout
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The pinout definitions are shown in Table
July 2022
2.
The pin definition of the device's 8Pin female socket is shown in Figure 3 and Table 1.

AFM0725
Response time
PBT
9ÿ24V DC
Power consumption
0.8MPa
AFM0725 pinout
±1%FS
Table 3. AFM0725 Specifications and Mechanical Parameters
output method
Operating temperature
length
model
-10~+60ÿ
0~25L/min
gas
56g
Display method
UL2464
maximum work
Shell material
describe
pinout
Repeatability
50ms
PBT
precision
RS485, NPN open collector output, 1~5V linear voltage output
Air (25°C, 1 standard atmosphere)
0.85W (typ.)
Pressure
Standard Calibration
parameter
Display unit cumulative flow: L (ft3×10-1) Instantaneous flow: L/min (CFM×10-2)
Duct material
material
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range
±3%FS
30cm
Power supply
LCD display
product weight
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2. AFM0725 technical indicators and mechanical
July 2022
parameters

Figure 5. Piping Diagram
Figure 4. AFM0725 Dimensions (Unit: mm)
3. Product dimension drawing and piping method
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(2) Please avoid installation with the display face
July 2022
down.
(1) For the piping of the product inlet/outlet, please reserve a straight pipe part with a length of more than 12cm, and the inner diameter of the straight pipe is less than 4mm (including 4mm).
, otherwise the accuracy may be affected by ±2%FS or more.
3.1 The dimensions of AFM0725 are shown in Figure 4.
3.2 Piping method, as shown in Figure 5.

As a slave, the default address is 0x01, which supports address modification and can be connected to the bus of multiple slaves.
The communication protocol is standard Modbus RTU. The host can be a computer, RS485 receiver and MCU controller, etc. AFM0725
The Modbus RTU communication register definition of AFM0725 is shown in Table 5.
The digital output communication mode of AFM0725 gas mass flowmeter is RS485 communication, and the communication parameters are shown in Table 4.
4. Product Communication Protocol and
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Output
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stop bit
data bits
parity none
communication rate
8
July 2022
bits
1 person
start bit
4800/9600/19200/115200bps
Communication parameters
Protocol format
1 person
describe
Table 4. RS485 Communication Parameters
RTU
4.1 RS485 communication

/
11520
0x0006
Low bit: 0x02d7
1: The accumulated flow is reset to zero
0~1
0~1
read only
(lower 16 bits)
10
Read and Write 03/06
0~1
Such as AFM0725 —> 0x02d5
0x062a
1: Alarm on
/
(higher 16 bits)
Cumulative flow
0x003A
or 1920 or
1 Lower limit alarm flag
base number
Example: 157.8L/min
0x0039
0x0034
03
/
0~1
0x0032
1
0~65535 read only
0: Alarm off
1: reserved
0~3
Cumulative flow
0~2000 read and write 03/06
0x0037
1 language device
The number of the model is directly converted to 16
Remark
1 Alarm switch
6: Oxygen (O2)
Read and Write 03/06
High bit: 0x4996
0: The cumulative flow remains unchanged
03
0x0115
1: Lower limit alarm
Value range Read and write attribute function code multiple register information
Read and Write 03/06
0: Chinese
0x0004
1 Accumulated flow reset
/
0x0030
Example: 27.7ÿ
5: Helium (He)
1: CFM×10-1
480 or 960
read only
Example: 123456789.5L
10
0x0036
Read and Write 03/06
/
0: No alarm for lower limit
address
1~6 4: Carbon dioxide (CO2)
0: L/min
10
0x003B
Read and write 03/06 1/10 baud rate
model
10
03
(L/min)
0x0035
03
10
03
—> 0x00Fa
1 flow unit
1: Upper limit alarm
0~65535 read only
03
3: Argon (Ar)
03
0~1
03
0~2000 read and write 03/06
0x2d00
0x0033
1 Device status information
0x0000
Alarm lower limit value
4800, 9600, 19200,
2: Nitrogen (N2)
0x0031
0x0003
For example: set 25L/min
—> 0x0032
Such as: baud rate 115200 —>
03
0x0002
(L/min)
1 slave address slave address, only supports 1-32
0x0005
0x0001
register
0x0038
/
read only
10 Instantaneous flow
0~65535 read only
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1: Air (AIR)
0~9999 read only
temperature
1 Upper limit alarm flag
0~65535 read only
For example: set 5L/min
115200
0~1
1 Software version such as V0001—>0x0001
0~65535 read only
Alarm upper limit value
1~32 Read and write 03/06
Read and Write 03/06
0: No alarm for upper limit
Table 5. Modbus RTU Communication Register Definitions
1 Gas fluid type
0: The flow meter is normal
2: EEPROM abnormal
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1: The sensor is abnormal
3: Both the sensor and EEPROM are abnormal
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When the host needs to change the slave address of AFM0725 to 0x02, it needs to rewrite the value of the 0x0035 register. Host write register value
When the host reads the instantaneous flow value of AFM0725 (the default slave address of the device is 0x01), the host sends a command to AFM0725.
The command format is shown in Table 8.
When the host receives the data returned by AFM0725, the data format is shown in Table 7.
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The data format is shown in Table 6.
July 2022
03
1
slave address
1 register read
write a single register
read 1 register
Table 7. Format table for host to receive AFM0725 register data
Number of read registers × 2
Number of bytes of information sent by the host Sending information example (Hex)
2
2
According to the above example, the host sends the
function code
-
function code
2
Description of the meaning of the information
0001
1
-
2
Communication slave address
Register 0x0000 stores the instantaneous flow value
Received data bytes =
Table 8. Format Table for Host Send Write Register Command
CRC code is used for verification
03
read multiplex register
CRC code
1
(Hex)
02
slave address
CRC code
Number of bytes of information sent by the host Sending information example (Hex)
2
-
B84B
site
CRC code
Description of the meaning of the information
register data
read multiplex register
840A
-
write data 0002
1
Communication slave address
062A
01
slave address
Table 6. Format table for host to send read register command
0000
01
2
Register 0x0035 holds the slave ground
Read the number of registers
The number of bytes of information sent by the slave
10, the final result is 157.8L/min
data input
0035
01
function code
2
1
CRC code is used for verification
receive information
Receive data bytes 1
Description of the meaning of the information
0002
1
CRC code is used for verification
06
register start address
The meaning of the received data
Convert to decimal and divide by
register address
1805
Communication slave address
2
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The load in Figure 6 may be an alarm device, such as a warning light. By default, the alarm function is turned off, there is no upper and lower limit alarm, the two NPNs (equivalent to switches)
are in the open state, the load circuit is open, and no current flows. Turn on the alarm function, after setting the upper limit and lower limit of flow, when the flow value is higher than the upper limit or lower
than the lower limit, the corresponding NPN is closed, the current flows through the load, and then the alarm device can start to work. When the upper and lower limit alarms are turned on, an alarm will be
issued when the instantaneous flow value is higher than the upper flow limit value or lower than the flow lower limit value. For example, if the upper limit is set to 20 and the lower limit is set to 5, when the
instantaneous flow value is lower than 5L/min, the NPN open collector output port corresponding to external output 2 is closed, and when it is higher than 20L/min, the NPN open collector output
port corresponding to external output 1 is closed. closed, alarm.
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The C language code for calculating the CRC code is as follows:
AFM0725 has 2 NPN open collector output ports, 2 NPN open collector output ports correspond to external output 1 and external output respectively
Output 2, external output 1 controls the upper limit alarm, and external output 2 controls the lower limit alarm. If the AFM0725 lead wire is purchased, the external output 1 (NPN1) corresponds to the
gray wire, the external output 2 (NPN2) corresponds to the brown wire, and the GND corresponds to the black wire and the orange wire. The wiring diagram is shown in Figure 6.
4.2 NPN open collector output
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crc ^=*ptr++;
for(i=0;i<8;i++){ if(crc &
0x1){ crc>>=1;
crc^=0xA001;
} else crc>>=1;
} return crc;
unsigned int crc= 0xFFFF;//initialize initial value
unsigned char i; while(len--) {
}
}
// *ptr communication send or receive data byte
array, // len send or receive data byte length (excluding
CRC code) // return the calculation result of CRC code,
high byte first unsigned int CRC16(unsigned char * ptr, unsigned char len) {
Figure 6. Schematic diagram of NPN control upper and lower limits
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4.3 Voltage output
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5. Work interface and interface operation
July 2022
The voltage output of the AFM0725 is a linear output. The relationship between voltage and flow is: Voltage (V)
= 1 + Instantaneous flow (L/min) × 0.16
Figure 8. The cumulative flow
interface menu page has 4 levels, and the function description of each level is shown in Table 9.
When the lock screen icon (ÿ in Figure 7) is on, press and hold the setting key for 5 seconds to unlock and enter the menu page, and press the up and down keys to select the parameters to
be set. If there is no operation within 30 seconds, the system enters the lock screen state. When the alarm switch status icon (ÿ in Figure 7) is on, it means the alarm function is turned on, and when
there is no icon, it means the alarm is turned off. To view the cumulative flow, on the main page, press the down key to jump to the cumulative flow display interface, as shown in Figure 8.
Figure 7. Introduction to screen icons
ÿ is the 485-communication address; ÿ is the fluid type; ÿ is the alarm switch status; ÿ is the 485 communication
status; ÿ is the lock screen icon; ÿ is the instantaneous flow; ÿ is the instantaneous flow unit.
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parameter settings
/
/
quit
AFM0725
19200, 115200 four baud rates can be selected)
Alarm function on or off
/
certificate
Level 1 menu Level 2 menu Level 3 menu
Flow reset
Set the lower limit of flow, when the alarm function is turned on, the flow is lower than the flow
Communication settings
1
/
Reserved, the default is Chinese
/
name
Set the baud rate of the transmitted data (4800, 9600,
Alarm switch
Product Manual
View the model, range, version, and SN code of the device
Table 9. Function introduction
language settings
quit
/
system settings
/
1 set
Back to one level menu
Device Information
Select the type of gas to be tested
packing list
Alarm system
Back to one level menu
/
/
quit
AFM0725 pinout
Factory reset the product
/
Back to secondary menu
/
Upper limit alarm
Accumulated flow value reset to zero
Function
Restore Factory
Select the communication address of 485 (1-32)
Traffic cap
quit
1 piece
Lower flow limit
Back to one level menu
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quit
Set the upper limit of the flow rate, when the alarm function is turned on, the flow rate is higher than the flow rate
/
baud rate
quantity
back to main interface
flow rate unit
485 address
Lower limit value alarm
1 serving
/
Fluid selection
Unit switching between L/min and CFM
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(Available for AIR, N2, Ar, CO2, He, O2 gases)
6. Packing List

12 months
Product Category
AFM0725 Gas Mass Flow Meter
warranty period
6 months
Warranty Period Description
Wire or other parts
Warning and Personal Injury
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Quality Assurance
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July 2022
Guangzhou Aosong Electronics Co., Ltd. provides the direct purchasers of its products with the quality assurance in the following table (calculated from the date of shipment),
The final interpretation right of this product belongs to Guangzhou Aosong Electronics Co., Ltd.
Do not use this product in safety protection devices or emergency stop equipment, or in any other application where personal injury may result from failure of this product,
unless there is a specific purpose or authorization for use. Refer to the product data sheet and instructions before installing, handling, using or maintaining this product. Failure to follow
the recommendations could result in death or serious personal injury. The company will not
The technical specifications are indicated in the product manual of Aosong Electronics. If the product is found to be defective during the warranty period, the company will provide a free
The company is only responsible for products that are defective when used in applications that meet the technical conditions of the product. The company should
Copyright © 2022, ASAIR®
Bear all compensation for personal injury and death arising therefrom, and exempt from any claims that may arise from company managers and employees, as well as affiliated
agents, distributors, etc., including: various costs, claims costs, attorney fees Wait.
Repair or replacement service.
No guarantee is made for use in non-recommended special scenarios. The company also does not make any commitment to the reliability of the product applied to other non-company
supporting products or circuits.
This manual is subject to change without notice.