问如何用python读取RS485温度计数据

EN

THT-02 follows the RTU information frame protocol. In order to ensure the integrity of the information
frame, a pause time of 3.5 characters or more is required at the beginning and end of each information
frame, each byte of the information frame needs to be transmitted continuously. If there is a pause time greater than 1.5
characters, the sensor will treat it as invalid information and will not respond.

The sensor allows the host to use the function code 03 to read the temperature and humidity measurement
value of the sensor and other information. The information frame format of the 03 code is as follows：

Field Description Example

Slave address               01
Function code               03
Register address high byte  00
Register address low byte   00
High byte of query quantity 00
Low byte of query quantity  08
CRC check code low byte     44
CRC check code high byte    0C

Sensor response information frame

Slave address               01
Function code               03
Return the number of bytes  10
Temperature data high byte  00
Temperature data low byte   FA
Humidity data high byte     02
Low byte of humidity data   58
1 high byte reserved        00
1 low byte reserved         00
2 high byte reserved        00
2 low byte reserved         00
Address code high byte      00
Address code low byte       01
Baud rate high byte         25
Baud rate low byte          80
Hardware version high byte  06
Hardware version low byte   00
Software version high byte  00
Software version low byte   0A
CRC check code low byte     D4
CRC check code high byte    64

import time
import sys
import serial

ser = serial.Serial(
    port='/dev/ttyS0', baudrate=9600,
    parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE,
    bytesize=serial.EIGHTBITS, xonxoff=False,
    rtscts=True, dsrdtr=True, timeout=3)

print(ser.name)
ser.write(br'\x01\x03\x00\x00\x00\x08\x44\x0C\r\n')
ret=str(ser.readlines())
print(ret)

from pymodbus.client.sync import ModbusSerialClient as ModbusClient

client= ModbusClient(
    method = "RTU", 
    port = "/dev/ttyUSB0", 
    stopbits = 1, 
    bytesize = 8, 
    parity = 'N', 
    baudrate=9600)

client.strict = False
connection = client.connect()

FORMAT = ('%(asctime)-15s %(threadName)-15s'
' %(levelname)-8s %(module)-15s:%(lineno)-8s %(message)s')
logging.basicConfig(format=FORMAT)
log = logging.getLogger()
log.setLevel(logging.DEBUG)

rr = client.read_holding_registers(0, 2, unit=5)
log.debug(rr)
print(rr.registers)

client.close()

import time, serial
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BOARD)
GPIO.setup(12, GPIO.OUT)

s = serial.Serial(
    port = '/dev/ttyS0',
    baudrate = 9600,
    parity = serial.PARITY_NONE,
    stopbits = serial.STOPBITS_ONE,
    bytesize = serial.EIGHTBITS,
    xonxoff = False,
    rtscts = False, 
    dsrdtr =True,
    timeout = 1
)

temp = b'\x05\x03\x00\x00\x00\x01\x85\x8e' 
#temp response \x03\x02\x00\xea\xc8\x0b => \x00\xea = 234 => 23.4 C

humidity = b'\x05\x03\x00\x01\x00\x01\xd4\x4e' 
# humidity response  \x03\x02\x01\xda\xc9\x8f => \x01\xdd = 474 => 47.4 %

GPIO.output(12, 1)
time.sleep(0.01)
#s.write(temp)
s.write(humidity)
time.sleep(0.01)
GPIO.output(12, 0)
res = s.readlines()
print('reading')
print(res)

GPIO.cleanup()
s.close()

from pylibmodbus import ModbusRtu


# For Python 3.x you have to explicitly indicate ASCII enconding
client=ModbusRtu(
    device="/dev/ttyS0".encode("ascii"), 
    baud=9600, 
    parity="N".encode("ascii"), 
    data_bit=8, 
    stop_bit=1
)

#Read and set timeout
timeout_sec = client.get_response_timeout()
print(timeout_sec)
client.set_response_timeout(timeout_sec+1)

#Connect
client.connect()

SERVER_ID=5
BCM_PIN_DE=18
BCM_PIN_RE=17

#Set Slave ID number
client.set_slave(SERVER_ID)

#Enable RPi GPIO Functions
client.enable_rpi(1)

#Define pin numbers to be used as Read Enable (RE) and Drive Enable (DE)
client.configure_rpi_bcm_pins(BCM_PIN_DE,BCM_PIN_RE)

#Export pin direction (set as outputs)
client.rpi_pin_export_direction()

#Write Modbus registers, 10 starting from 0
#client.write_registers(0, [0]*10)

#Read 10 input registers starting from number 0
result=(client.read_registers(0, 1))

#Show register values
print(result[0])

#Release pins and close connection
client.rpi_pin_unexport_direction()
client.close()