Python pymodbus tcp同步客户端无法在连接失败时捕获错误

使用来自的

pymodbus

示例 它工作正常，连接到PLC并读取保持寄存器。 但我有一个问题。当PLC关闭时，该代码无法捕获断开连接的错误

from pymodbus.client.sync import ModbusTcpClient as ModbusClient
UNIT = 0x1
def run_sync_client():
  client = ModbusClient('192.168.1.190', port=502)  
  client.connect()
  rr = client.read_holding_registers(1, 4, unit=UNIT)
  # follwoing will write value 10 or 20 to address 1 
  rq = client.write_register(4, 20, unit=UNIT)  
  client.close()
  print (rr)
  print (rr.registers) ## This reads from input registers of the Modbus Slave / Server 

  if __name__ == "__main__":
      run_sync_client()    

我试了，试了。。然后，如果client.connect（）。有人能建议怎么做吗。

---

谢谢

请尝试下面的代码，而不是

client.connect（）

和

print（rr.registers）

：

---

好的，通过更多的阅读和试验，我让它工作如下。我可能错了。但我想分享我的代码，以帮助像我这样的新手有一个起点。 代码如下所示

import logging
UNIT = 0x1


def run_sync_client():
    try:
        #client = ModbusClient('192.168.1.190', port=502)  
        client = ModbusClient('localhost', port=502)  
        client.connect()
        #connected =1

    except:
        print("modbus error")
   # "Read write registeres simulataneously")
    try:
            rr = client.read_holding_registers(1, 4, unit=UNIT)
            # following will write value 10 or 20 to address 1 
            rq = client.write_register(4, 20, unit=UNIT)  
            # close the client
            client.close()
            print (rr)
            print (rr.registers) 
    except Exception as e:
            print ("Modbus Connection returned Error ",e)
if __name__ == "__main__":
    run_sync_client()

这工作正常，通过tcp从plc获取值。现在我正在研究异步连接。会带着一些疑问回来，然后会有一些答案（如果有的话）；）

import logging
UNIT = 0x1


def run_sync_client():
    try:
        #client = ModbusClient('192.168.1.190', port=502)  
        client = ModbusClient('localhost', port=502)  
        client.connect()
        #connected =1

    except:
        print("modbus error")
   # "Read write registeres simulataneously")
    try:
            rr = client.read_holding_registers(1, 4, unit=UNIT)
            # following will write value 10 or 20 to address 1 
            rq = client.write_register(4, 20, unit=UNIT)  
            # close the client
            client.close()
            print (rr)
            print (rr.registers) 
    except Exception as e:
            print ("Modbus Connection returned Error ",e)
if __name__ == "__main__":
    run_sync_client()