You want to use an external editor, configured on Tools > Options > Editor > External Editor, using the DDE interface (Windows Dynamic Data Exchange). If you get the following error message:
A DDE conversation with the service xyz could not be established
.. you should ensure that the service application "xyz" has DDE enabled.
Turning on the DDE service may be an option in a menu somewhere in the external editor application, or it may be an option in a configuration file. Some versions of CodeWright, for instance, has this in cwright.ini. There is a section LibPreLoad as below.
; Uncomment to preload desired libraries during startup:
Also note that you may need to install this DLL, if it was not selected during installation.
IAR Embedded Workbench first asks Windows for the specified service, and if none is available, the application specified under Editor is started and the question is asked again. If the service still is not available, the error message above is given.
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