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Does a router tells a device to close a TCP connection?

  1. Feb 11, 2016 #1
    Does a router tells a slave device to close a TCP connection, if the router loses connect from the master device ? So, I have a Qterm-g72 HMI and I am trying to connect it to a Moxa over TCP Modbus. This only works if a Computer or a router is between the Moxa and the HMI. I am trying to found out why. So, my question is does a computer or a router close the connection to the Moxa if it lose it from the HMI ? The HMI is the master so it does the talking and the Moxa is the slave. The Moxa does not know to lost the connection if the HMI does not tell is to close with TCP, so I wanted to know if the Computer or Router would do that ?
    Also does anyone else think they might know why the HMI and the Moxa will not work with a router or a computer in between?
  2. jcsd
  3. Feb 12, 2016 #2
    Which Moxa device are you using?
    We had some serious issues with the Moxa Nport devices and Modbus.

    But no a router doesn't provide any functionality other than routing the packets between device.

    When you don't have the router installed does it work at all and then stop? Or just not work period?
    Have you tried using a cross over ethernet cable?
  4. Feb 13, 2016 #3

    jim mcnamara

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    Staff: Mentor

    @cpscdave Is correct. routers simply take packets and move them around. What makes your think a router is 'telling' some other network object to close a port? Routers are really dumb - they simply filter stuff, and sometimes drop what they have been instructed to - as bad packets. None of this explicitly requests a 'close operation' on anything that I know of.
  5. Feb 13, 2016 #4


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    Staff: Mentor

    Mine allows an automatic internet disconnection depending on idle time and a dayly forced shutdown (with probably an automatic restart.)
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