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Generating Macro Key sequences using The Mule™ Interface

This page is under development- contact Technical Support if you need help

What is a Macro Key operation

There are many situations where it is convienient to run an operation simply by pressing a single key. For example Micosoft Windows has the ability to 'attach' an applications program to a single keystroke which runs when that key is pressed.

To avoid conflicts and unwanted interactions it is usual to choose a 'special' key- one which is unlikely to be used by another program. The 'special' key is generally a combinational keystroke.

Combinational Keystrokes

Combinational keystrokes are generated by pressing more than one key in a particular order. You already use 'combinational keystrokes' without giving it a second thought. For example the character 'A' is produced by first pressing and holding the 'shift' key, then pressing the 'A' and finally releasing the 'shift'.

'Shift A' would probably not be a good choice for a macro key because it is a key already heavily used. A better choice would be a key sequence not already in use. For example 'Shift F1' or 'Alt F1' might be better choices.

Using 'The Mule' to emulate a Macro key

The Mule can generate every possible combinational keystroke. Even complex keystroke using three (or more) keys are no problem for The Mule. For example 'Control Alt F1' or even 'Shift Control Alt F1' would be well within the capability of 'The Mule'. (However the PC may not be able to differentiate all possible complex combinational keys.)

The Mule requires an RS232 data stream encoding the PC scancodes necessary to emulate any particular key sequence. This can come from another computer running a program which calculates the necessary keystrokes and sends them to The Mule. This approach is taken in many process control situations. However there are applications where a simpler approach is required.

If it were possible to create a barcode containing the required data then a simple RS232 scanner and Mule combination could be used as an alternative to the keyboard- thus eliminating errors and speeding repetitive jobs.

Putting it all together

The requirements for a Barcode Macro Key system are these...

  1. 'The Mule' interface.
  2. Suitable barcode scanner and PSU.
  3. Printed Barcode.

The Mule

Unless you ask otherwise The Mule is generally shipped with scancode mode disabled. It is a simple matter to enable scancode Mode. Simple fit the link (supplied) inside the case as described in the Mule User Manual.

Barcode Scanner

The scanner should preferably have the ability to read Code 128 barcodes or at least Full ASCII Code 39 barcodes. You should ensure the scan width is adequate to cover the whole width of your barcode. The scanner needs to have a RS232 interface (Not a regular wedge interface). It should be preferably be programmed to use a CTS/RTS handshake but 'No Handshake' will work well for most applications. Suitable barcode scanners can be purchased from BarcodeMan.com and if you tell us we will program it and set it up so you just need to plug it into The Mule. There is no additional set up cost- we just like to be helpful.

The Barcode

There are two barcode types suitable. Code 128 (the best choice) and Code 39.

Code 128

Code 128 can produce all the codes necessary. In addition it is a compact barcode enabling more data to be fitted into a single barcode. The downside is that the code is slightly harder to produce than Code 39 and requires a little more precision in the print process. Nevertheless Code 128 is far and away the best code to use for purpose.

Code 39

Code 39 can be used for the purpose but the Barcode Scanner MUST be capable of (and set up for) 'Full ASCII Code 39'. This is because regular Code 39 cannnot encode the special ASCII codes (Shift In and Shift Out) necessary to switch The Mule into Scancode Mode. Code 39 uses more space to encode the same data as Code 128 however it is easy to produce quality Code 39 Barcodes with ABC TrueType Fonts.

Using Barcode Mill to generate Macro key barcodes

Barcode Mill is a web application which generates barcodes. Here we have set up a special form to create barcodes for your Macro Key applications.

Generate your Macro Key barcode here

Note: Keyboards differ from country to country. Although the scancodes are mapped to the same physical key the arrangement of the of the printed keycaps vary from country to country. This web page assumes the USA keyboard layout.

Select the barcode type
Code 128 (preferred)
Code 39

Select 1 or more key modifiers
Shift
Control
Alt

Select the key (function keys only at present)


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