Host Engineering Forum

General Category => Do-more CPUs and Do-more Designer Software => Topic started by: Henryp on November 08, 2017, 03:02:02 PM

Title: Using a non standard Modbus port with a Do More
Post by: Henryp on November 08, 2017, 03:02:02 PM

In the past for security reasons I would move my Do More Modbus port to a location other than 502. I just installed a new Do More and updated it to version 2.1 firmware and it now appears that when I change the Modbus port number it doesn't move it off of port 502. Attached is a screen shot showing that the port has been change but another PLC on the network is talking to it but on port 502.

Title: Re: Using a non standard Modbus port with a Do More
Post by: BobO on November 08, 2017, 03:31:12 PM

It looks like there may be a bug updating the existing server. It appears to take the change sometimes and not others, but it always seems to work following a power cycle.

Please confirm that it will take the port after a restart.

Title: Re: Using a non standard Modbus port with a Do More
Post by: BobO on November 08, 2017, 04:12:24 PM

It's not a bug...I figured it out. The port that you configure is the port that the server listens on to establish new connections, but changing it doesn't remove any existing connections. The default client inactivity timeout is 60 seconds, so if an existing device stays connected, and talks within 60 seconds, it'll keep that connection open.