title: Creating async modbus server python problem
body: <p>I am new to Python and trying to create a modbus server with pymodbus module. I follow tutorial on <a href="https://github.com/SimplyAutomationized/modbus-tcp-tutorials/blob/master/pi_gpio_modbus_tcp_slave.py" rel="nofollow noreferrer">link</a>, but when I run script I got an error:</p>
  
  <pre><code>$ python2.7 server1.py    
  INFO:pymodbus.server.async:Starting Modbus TCP Server on 192.168.1.100:502    
  Traceback (most recent call last):    
  File "server1.py", line 83, in &lt;module&gt;    
  StartTcpServer(context, address=("192.168.1.100", 502))    
  File "/home/pi/.local/lib/python2.7/site-packages/pymodbus/server/async.py",     
  line 255, in StartTcpServer    
  reactor.listenTCP(address[1], factory, interface=address[0])    
  File "/home/pi/.local/lib/python2.7/site-     
  packages/twisted/internet/posixbase.py", line 495, in listenTCP    
  p.startListening()    
  File "/home/pi/.local/lib/python2.7/site-packages/twisted/internet/tcp.py",     
  line 1363, in startListening    
  raise CannotListenError(self.interface, self.port, le)    
  twisted.internet.error.CannotListenError: Couldn't listen on     
  192.168.1.100:502: [Errno 13] Permission denied.    
  </code></pre>
  
  <p>Anyone can help me solve my problem, Thanks in advance.</p>
  
  <hr>
  
  <p>[<strong>UPDATE</strong>]:</p>
  
  <pre><code>$ sudo python2.7 server1.py    
  Traceback (most recent call last):    
  File "server1.py", line 12, in &lt;module&gt;     
  from pymodbus.server.async import StartTcpServer    
  ImportError: No module named pymodbus.server.async    
  
  $ python -V    
  Python 2.7.13
  
  $ sudo python server1.py
  Traceback (most recent call last):
  File "server1.py", line 12, in &lt;module&gt;
  from pymodbus.server.async import StartTcpServer
  ImportError: No module named pymodbus.server.async    
  </code></pre>
  
  <p>I tried "sudo" already and got an error, it looks like when I use "sudo" the modules isn't on right spot...</p>