Modbus設備無故停止通訊

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我的公司已經購買了幾個具有modbus功能的房間溫控器。那些來自中國。當我在Modbus RTU上與他們交流時，會發生有趣的事情。設備有時不會迴應我。然後在接下來的民意調查中，他們有時會迴應但最後，在一段時間之後，不管一小時還是兩天，他們完全停止響應，並且我從modbus master獲得一些錯誤。我使用串口分析器來查看發生了什麼。我做了所有的硬件檢查點（端接電阻等）。我嘗試了許多modbus大師。但即使只連接了一個恆溫器，也會發生問題。具體到這個問題，我用Python開發了自己的modbus master。最好的部分是，我使用最小的modbus庫，每次調查後我都有機會關閉端口。但是，即使我的modbus主程序繼續輪詢，恆溫器也會完全停止響應。不知何故，我必須通過編程來解決這個問題。我不能總是重新啓動恆溫器來解決通信問題。Modbus設備無故停止通訊

這裏是我的代碼：

import os 
import sys 
import sqlite3 
import time 
import datetime 
import minimalmodbus 
minimalmodbus.CLOSE_PORT_AFTER_EACH_CALL=True 

PORT_NAME   = '/com5' 
SLAVE1_ADDRESS  = 1 
SLAVE2_ADDRESS  = 2 
SLAVE3_ADDRESS  = 3 
BAUDRATE   = 9600 # baud (pretty much bits/s). Use 2400 or 38400 bits/s. 
TIMEOUT    = 0.4 # seconds. At least 0.2 seconds required for 2400 bits/s. 
MODE    = minimalmodbus.MODE_RTU 

sqlite_file = 'ModbusTable.db' 

instrument1 = minimalmodbus.Instrument(PORT_NAME, SLAVE1_ADDRESS, MODE) 
instrument1.serial.baudrate = BAUDRATE 
instrument1.serial.timeout = TIMEOUT 
instrument1.debug = False 
instrument1.precalculate_read_size = True 

instrument2 = minimalmodbus.Instrument(PORT_NAME, SLAVE2_ADDRESS, MODE) 
instrument2.serial.baudrate = BAUDRATE 
instrument2.serial.timeout = TIMEOUT 
instrument2.debug = False 
instrument2.precalculate_read_size = True 

instrument3 = minimalmodbus.Instrument(PORT_NAME, SLAVE3_ADDRESS, MODE) 
instrument3.serial.baudrate = BAUDRATE 
instrument3.serial.timeout = TIMEOUT 
instrument3.debug = False 
instrument3.precalculate_read_size = True 

print ('Okuyor') 


while 1: 

    # Connecting to the database file 
    conn = sqlite3.connect(sqlite_file) 
    c = conn.cursor() 

    try: 
     values1 = instrument1.read_registers(40005, 2) 
    except IOError: 
     print ('Timestamp: {:%Y-%m-%d %H:%M:%S}'.format(datetime.datetime.now())+"Failed to read from instrument1") 

    # C) Updates the pre-existing entry    
    c.execute("""UPDATE ModbusData SET SetPoint = ? ,ActualTemp = ? WHERE ID= ? """, 
     (values1[0],values1[1],1)) 

    time.sleep(0.5) 

    try: 
     values2 = instrument2.read_registers(40005, 2) 
    except IOError: 
     print ('Timestamp: {:%Y-%m-%d %H:%M:%S}'.format(datetime.datetime.now())+"Failed to read from instrument2") 

    # C) Updates the pre-existing entry    
    c.execute("""UPDATE ModbusData SET SetPoint = ? ,ActualTemp = ? WHERE ID= ? """, 
     (values2[0],values2[1],2)) 

    time.sleep(0.5) 

    try: 
     values3 = instrument3.read_registers(40005, 2) 
    except IOError: 
     print ('Timestamp: {:%Y-%m-%d %H:%M:%S}'.format(datetime.datetime.now())+"Failed to read from instrument3") 

    # C) Updates the pre-existing entry    
    c.execute("""UPDATE ModbusData SET SetPoint = ? ,ActualTemp = ? WHERE ID= ? """, 
     (values3[0],values3[1],3)) 

    time.sleep(0.5) 

    # Committing changes and closing the connection to the database file 
    conn.commit() 
    conn.close()

這裏是恆溫如何執行：