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FabulaTech Forum Serial Port Solutions Serial Port Redirector (Moderators: Andrew, Tim_GaliullinFT, Sergey_Jarovski) Optimization for Slow Links

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Topic: Optimization for Slow Links (Read 5403 times)

Kumar
FabulaTech Forum Newbie

Posts: 3

Optimization for Slow Links
on: Oct 20^th, 2012, 5:56am

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Hello,

i am trying to set up a remote access to our PLC.
for that i have an embedded device hard wired to the plc (rs232). the embedded device forwards the rs232 traffic via tcp-rfc2217 to my host machine where i am running Serial Port redirector.

the connection to the embedded device is a GSM/UMTS link with RTT between 500-800 ms, sometimes over 2000ms

via lan it works perfectly but over the wan link its really slow and the software i am using to access the PLC (codesys) times out so i can only access the plc 3/10 times

is there a way to integrate a certain timeout period for each packet in serial port redirector?

maybe you can help me with this issue

thank you

regards
kumar

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Serge Frost
FabulaTech Forum Full Member

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Posts: 169

Re: Optimization for Slow Links
Reply #1 on: Oct 22^nd, 2012, 7:01am

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Hello,

Are you familiar with "PortMon" software? I need you to take the logs of your PLC when it works correctly via LAN and when it works via Internet.

I will compare these logs and will try to find the source of the issue.

You can download "PortMon" from Microsoft Official Web Site or from our FTP server:
ftp://castle.colonet.net/upload/support_tools/PortMon/

Send these log files to my email: support@fabulatech(dot)com

Thanks!

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Kumar
FabulaTech Forum Newbie

Posts: 3

Re: Optimization for Slow Links
Reply #2 on: Oct 22^nd, 2012, 7:19am

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Hello,

thanks for your fast reply. it seems portmon is not available for windows 7 64 bit systems.

see: http://answers.microsoft.com/en-us/windows/forum/windows_7-hardware/portmon-equivalent-for-win-7-64-bit/187c4fe0-2e1c-415b-9c14-3e65f9901fb5

do you have an alternative?

thank you

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Serge Frost
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Posts: 169

Re: Optimization for Slow Links
Reply #3 on: Oct 22^nd, 2012, 7:55am

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Yes, unfortunately it doesn`t work on 64-bit systems.Ok, lets do it in another way.

Here is the link for downloading HyperTerminal:

ftp://castle.colonet.net/upload/support_tools/HyperTerminal/

Download it on two computers and transfer a big file (>5 Mb) via Internet. And let me know the results of this little test.

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Kumar
FabulaTech Forum Newbie

Posts: 3

Re: Optimization for Slow Links
Reply #4 on: Oct 22^nd, 2012, 8:27am

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i am really sorry, but unfortunately i dont have any gprs modem available to insert the simcards i am using for my embedded linux devices (they already have the modem built in)

is there anything else i can test?

i am looking for a setting to make the virtual port reliable even with high rtt's (400-1000ms)

e.g. com0com offers:
AddRTTO=<n> - add <n> milliseconds to the total time-out period for read operations (0 by default)
AddRITO=<n> - add <n> milliseconds to the maximum time allowed to elapse between the arrival of two characters for read operations (0 by default)

maybe you have something similar or even better?

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Serge Frost
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Posts: 169

Re: Optimization for Slow Links
Reply #5 on: Oct 25^th, 2012, 5:57am

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Hi,

I tried to reproduce this issue. I set bandwidth to 9,6 kB with the help of NetLimiter and tried to work with Serial Port Redirector. I was working slowly but it worked.

Ok, is it possible to get "WireShark" logs? (http://www.wireshark.org/) It is freeware and it works on all computers with all operating systems. I need logs when it works correctly in local network and when it works via internet. I will compare these logs and will try to find the source of the issue. Also please let me know your IP addresses and the number of TCP port in Serila Port Redirector so I can configure filters in WireShark.

One more questions. What is the speed of COM port opening in codesys?

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