Table of Contents

There is one known problems with using some swipe/scanner/reader in a Remote Desktop/Terminal Server environment. It is a problem with keyboard emulators in general. If the swipe is too fast (much faster than a person can type), then the order of the keys may get mangled when being transmitted from the local computer to the remote computer.

This is due to a feature (bug?) in the way windows keyboard messaging works. When you type the string “%aC”, Windows actually does this:

Message -> Shift Down

Key Pressed -> 5

Message -> Shift Up

Key Pressed -> a

Message -> Shift Down

Key Pressed -> c

Message -> Shift UP

Unfortunately, messages actually get handled differently in Windows than the key presses and this caused problem when sent from RDP. What the computer will can receive is …

Key Pressed -> 5

Key Pressed -> a

Key Pressed -> c

Message -> Shift Down

Message -> Shift UP

Message -> Shift Down

Message -> Shift UP

The received message is translated as “5ac” rather than %aB. There is a work-around in RDC when you are using full-screen, but it does alter some other keyboard behavior so it is best to have a slower swipe to avoid this problem.

Solution

Remote Desktop Settings allow you to change the way keystrokes are combined. To change this,

1. Run remote desktop but do not log in.

2. Click on the Show Options down arrow. (The exact look may change depending on your version of Windows.)

3. Click on the "Local Resources" tab. Look for the drop-down where it says Keyboard. Change the option to "On this computer".

4. Click back on the General tab and save your changes.

Side Effects

This change tells Windows to process the different keys on the local computer and then send key strokes up to Remote server. For all standard keys this works fine. However, “special keys” like Control-Tab, Windows-R, and other combination keys do not have a “representation” that can be sent. They are only handled as key-combinations. Therefore, when this option is enabled these special keys will not work. There is no known work-around for this, but most typical users do not use these keys anyway.

Source

Contributor: Cyrious Software

Date: 9/2013

Version: Control 4.0+