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PortServer TS 16 MEI serial data loop on power up

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We have had an issue with a PortServer TS16 MEI and I am hoping to get some assistance.

We have a unit that we use to collect logging data from 12 protocol converter cards. Each card has a RS-232 serial port that runs at 115200 8,n,1. The data is logged on a CentOS server and it uses the latest RealPort driver.

A month ago, we had power to the terminal server go down. It was out for 75 minutes. When the power came back, the terminal server started sending the logging messages coming into the serial port of the terminal server back into the protocol converter card. We were seeing an echo of the data on the line. This caused a flooding of the lines that run through the cards and basically caused a denial of service. The unit stayed in this echo mode for 17 minutes until it rectified itself without any intervention.

One night we tried doing some testing where we took the power down for 5 minutes and were unable to replicate the problem. On another night we took the power down for 75 minutes and were able to replicate the fault.
Is it possible to get some information on the boot process of these devices?

Do you know of any way this could happen?
I have a suspicion that the terminal server got to a certain point in the boot process and hung there. The problem rectified at the same time the logging started working again. My suspicion is it hung until the network side of the terminal server came back.

We use these in multiple parts of our business so we need to be sure the fault can not occur elsewhere.
Thanks for your time.
asked Jul 3, 2014 in Serial Servers by Thurmus New to the Community (1 point)

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3 Answers

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Though I'm unsure what firmware version you have running on your Portserver TS16 MEI, the product has been released for a few years so having the latest firmware is always recommended. I did glance over the release notes and didn't see anything which stood out as a possible cause of this issue, but the latest firmware is a good place to start.

Since it seems you're able to replicate the issue and have suspicion that it might be related to the network interface, one possibility that came to mind is that you could set one of the Portserver's serial ports for dev=term, then hook a Terminal/Laptop comm port up to it and do some tracing of the startup from a local console interface. Type "set trace ?" once you've accessed the Portserver's CLI for further information on the traceable options with this command.
answered Jul 3, 2014 by michaelt Veteran of the Digi Community (769 points)
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We are using 82000684_U3 12/19/2009 firmware.

Will give your suggestion a try.

answered Jul 3, 2014 by Thurmus New to the Community (1 point)
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Is there flow control implemented on the serial ports? If data is streaming into the serial ports and not being read from the host, the buffer may be filling up and trying to purge when the connection re-establishes with the host.
answered Jul 9, 2014 by userid0 Veteran of the Digi Community (2,158 points)