Performance problem with serial port on Win2012-R2 server

Guenter Haslinger
Guenter Haslinger used Ask the Experts™
Hello Experts

Performance problem with redirect serial port on Win2012-R2 server.

Our application is installed on Win2012-R2 server.
We start from Win7-client a remote desktop session.

Application has to sends data to a device over the serial port.
Device is connected to the serial port on the client machine.
The serail port is redirected from server to client (see screenshot).

The redirection of the serial port to the client machine works but is very slowly.
A request/response takes up to 3 seconds.

Similar configuration with Win208-R2 server works properly.
In this configuration takes a request/response appr. 100 miliseconds.

Do you have any idea what could cause this Problem ?

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Jackie Man IT Manager
Top Expert 2010

What is your version of RDP in windows 7?

RDP 7.1 Client
RDP 7.1 Client
RDP 8.1 Client
RDP 8.1 Client
After updating according to the link below, RDP client is of 8.1 version.

You need to follow the order of KB updates restart computer after applying each KB updates.

One stop downloads for Windows6.1-KB2574819-v2-x64.msu, Windows6.1-KB2830477-x64.msu, Windows6.1-KB2857650-x64.msu and Windows6.1-KB2913751-x64.msu.
Are all of the serial ports native com ports (i.e. 3F8, IRQ 4) or are they either PCI cards or USB?
Guenter HaslingerTest engineer


We updated the RDP client to 8.1 version but the performance problem is still pending.

On the client we use the native COM port.
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What is the serial device?
IT Manager
Top Expert 2010
In such case, you need to know the tsconfig,msc of your server 2012 R2 RDP gateway and the info below may be useful for you.

"Note that Windows Server 2012 installations no longer come with a tsconfig.msc. If you want to check the current COM port redirection setting, you might want to use a Windows client (7/Vista/XP) with the Adminpak installed or a Server 2008R2/2008/2003 with Terminal Services installed to run tsconfig.msc to connect to your Server 2012 RD session host."


Adminpak (Remote Server Administration Tools for Windows 7 with Service Pack 1 (SP1)):
Guenter HaslingerTest engineer


Sorry for the late reply

Our management decided to spend no more time to fix this bug ...

Thx for everything

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