Stop TCP Server

[Shammya Saha]

Hello

Is there any way to create multiple TCP servers? Looks like doing the following did not work

StartTcpServer(context=context, address=('127.0.0.1', 5020))

StartTcpServer(context=context, address=('127.0.0.2', 5020))

Like StartTcpServer, is there any function to stop the TCP server?

Regards

Shammya Saha

[sanju dhoomakethu]

StartTcpServer is blocking and hence you will not be able to call the second StartTcpServer . 

To answer the second question, You can use StopServer function to stop an async server, provided it is running on a separate thread. There is no option at present to stop Synchronous server. If you want to control Synchronous server, you can create ModbusTcpServer object and use shutdown method to stop the server.

server = ModbusTcpServer(context, framer, identity, address, **kwargs)

# Start server in a separate thread

# server.serve_forever()

# Shutdown

server.shutdown()

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[Galen Collins]

Also make sure you run each server on a different port. In this case you are trying to run both on the same port of 5020.

[Alexander Lutz]

Is it possible to run multiple modbus asynchronous servers from different IP addresses on the same machine? I'd like to keep the ports for the different IPs at default of 502.

as mentioned in the response to the above example, if I don't use threading, only 1 server is ran. So i added a second IP alias to my NIC card configuration (such that it looks like it is hosting 2 ip addresses). I then tried to use threading to start multiple instances of the modbus TCP server. When I do this, the "reactor" module is unhappy that I am trying to call it from another thread after it has already been called. 

Is there any way to run multiple asynchronous modbus servers from the same machine? That way I could use port 502 and scale the number of devices with IP address instead of port. If you you limit to one IP and one port then i can only max out at 255 devices, correct?

Here is what i was trying to do:

#set IPs for modbus gateways

port = 502

ip1 = "172.16.1.40"

ip2 = "172.16.1.41"

addy1 = (ip1,port)

addy2 = (ip2,port)

t1 = threading.Thread(target=StartTcpServer, args=[context,identity1,(ip1,port)])

t1.start()

t2 = threading.Thread(target=StartTcpServer, args=[context,identity1,(ip2,port)])

t2.start()