Design Specification for YB-X Digital Pressure Gauge
Please read this manual carefully before use, especially the "Precautions and Warnings" section!
The YB-X digital pressure gauge combines intelligent microprocessor technology and high-precision A/D conversion technology, using * * interpolation theory and approximation algorithm to ensure instrument accuracy; Reliable and mature LED Nixie tube display with high brightness and clear visibility; The shell is made of stainless steel, which is corrosion-resistant and resistant to mechanical pressure. The core body adopts sealing technology, which can be applied to various complex environments.
1. Parameters:
1.1 Operating Environment
Environmental temperature: -40 ℃~85 ℃
Environmental humidity: -10% RH~95% RH
Atmospheric pressure: (86~106) kPa
1.2 Display
LED Nixie tube 4-digit digital display
1.3 Power supply method
DC11~26V
1.4 Pressure Units
MPa
1.5 Overall dimensions
Ø50mm × 45mm
1.6 Cable length
1 meter (can be reserved according to the user)
1.7 Pressure interface
M10 * 1 (customizable according to user needs)
1.8 Overload pressure
120% FS overload, with YB-30 pressure temporarily within the range of 0-20Mpa to ensure accuracy, while other models ensure accuracy throughout the entire range.
1.9 Function
Communication method: RS485
Communication protocol: prepared according to user backend protocol
Upper and lower limit alarm (set any point alarm according to user needs)
2 specifications (default upper and lower alarm values)
3 Communication protocol
Sampling MODBUD (RTU) protocol, using read "read hold register: function 03" and write "write hold register: function 06"
3.1 Slave ID address
The default ID address of the slave is 0x01, which can be modified by modifying the register value, ranging from 0x01 to 0xFF, where 0x00 is the broadcast receiving address.
3.2 Read Holding Register (Function 0x03)
The host can read the slave register data through this function, and can simultaneously read one or more registers.
The slave response returns the function code, indicating that it is a normal response. The byte count "Byte count" indicates how many 8-bit bytes have been returned. It indicates the number of 8-bit bytes attached to the data area. When organizing response information in the buffer, the value in the "Bytes" area should be equal to the number of bytes in the data area of the information. When using RTU mode, 63H is sent in one byte (01100011). Eight bits are used to calculate the "number of bytes" in a unit, which ignores the method of composing information frames.
Explanation: The host reads the three register values starting from the host register address 0x01;
The slave returns 3 registers and 6 bytes of data.
For example, if the local ID address is 01 and you want to read the values from register 01 to register 03 of the digital table, send and receive commands as follows:,
01 (ID) 03 (Function Code) 00 01 (Register Start Number) 00 03 (Register End Number) 54 0B (CRC)
01 (ID) 03 (Function code) 06 (Number of data bytes) 03 E8 (Pressure value) 01 F4 (Low alarm setting) 00 04 (Filtering degree setting) 00 9C (CRC)
Note: The next step in calculating CRC requires swapping low and high bytes to obtain the final CRC-16 code.
3.3 Writing a Single Register (Function Code 0x06)
The host can write data to the slave register through this function, and can only operate on a single register. The format is as follows:
query
An example is a request to set the value of the 01H slave 0002H register to 01F4H.
response
The normal response to a preset single register request is to transmit the received data back after the register value changes.
For example, the command to set the ID number, which is to rewrite the 05 register, is as follows (set the original ID=01):
01 (ID) 06 (function code) 00 05 (register number) 00 03 (new ID number) D9 CA (CRC)
01 (ID) 06 (function code) 00 05 (register number) 00 03 (new ID number) D9 CA (CRC)
If correct, the sending and receiving data are consistent.
Register address reference value:
(1) 0x0001: Pressure value data, read-only, range according to specifications, unit: 0.01MPa
(2) 0x0002: Low alarm setting, read and write, 1000=10MPa, unit: 0.01MPa
(3) 0x0003: Filter level setting, read/write, 1, 2, 3, 4, default 4
(4) 0x0004: Baud rate setting, read and write, 1=9600bps, 2=19200bps, 3=600，4=1200, 5=2400, 6=4800, default 1
(5) 0x0005: Slave ID setting, read write, 0x01~0xFF, 0x00 broadcast, default to 0x01
(6) 0x0006: Reset, standby
(7) 0x0007: High alarm setting, read/write, write new alarm values, read current alarm values
4. Upper computer software settings
4.1 Software Design for Upper Unit Network
4.2 Upper computer calibration software design
5. Precautions
(1) It is strongly recommended that users not only connect A and B of RS485 when communicating with the instrument, but also connect all ground wires together (i.e. they must be grounded together). To avoid excessive level deviation, which may cause communication abnormalities or even burn out devices.
(2) When using MODBUS to modify parameter commands, it should not be too fast or too frequent. Because when modifying parameters, the instrument needs to write the parameters into the FLASH of the microcontroller, which takes a long time. At the same time, the number of erasures of FLASH is limited, so it is best not to modify them frequently.
(3) Although the sending and receiving speed of a single RS485 can reach 50ms, after multiple units are networked, due to the capacitance of the line, the interval period of each unit is better than 500ms.
(4) When the communication line is long or there are many communication channels, it is necessary to connect a 120 ohm resistor to the A and B terminals of the RS485 port of the host. Please refer to the following figure for network wiring:
(5) When the electromagnetic environment is complex or the circuit is long, other necessary measures need to be taken, such as selecting good bus cables, anti-static filtering, correct grounding, etc. The recommended method is to convert it into an optical signal for long-distance transmission. You can also make a signal concentrator out of the box, where one end communicates all signals locally and the other end converts them into fiber optic signals for long-distance communication.
(6) The RS485 industrial bus standard requires the use of a daisy chain connection method between devices, with 120 Ω terminal resistors connected at both ends. (As shown in Figure 1) Simplified connection can be achieved using Figure 2, but the distance between the "D" segment should not exceed 7 meters
Note: RS485 can have a theoretical maximum of 32, but in actual use, it only has about 12, which is related to the control chip of the computer side bus!
If there are many digital meters, a hub can be used for grouping, and then a hub can be combined to communicate with the host (computer).
The following figure shows the networking combination of 100 digital pressure gauges, and the specific usage must be confirmed with the hub manufacturer. The simple networking wiring of this instrument is shown in the following figure:
6. Warning
1. When plugging or unplugging cables, the power must be turned off first. It is strictly prohibited to plug or unplug cables with power to prevent damage to the communication chip!
2. Before powering on, make sure to repeatedly confirm that the power line (+, -) and communication line (A, B) are not short circuited.
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