Hi,

> A client has asked about the possibility of ruining  C# code on QNX 6.5 or 6.6

'ruining'? or 'running'? :)))

> To do this I would need to get a copy of Mono. Has anyone done this...

C#/.NET are around for a while. Many years ago I think someone tried to port an early version of MONO to QNX, but I 
don't remember if it went anywhere. 

There are multiple issues with MONO:
- MONO in itself only represents a subset of the classes that .NET provides. So if you want to port existing C# code, it
 is possible that some crucial functionality is absent from MONO.
- If you consider porting MONO to QNX, it might be sufficient to only port a subset. This would be the opposite case 
from the point above, i.e. your code only using a small subset of what MONO provides.
- From a legal point of view, AFAIK you are not allowed to run .NET code outside a Microsoft environment...

Depending on the size of the application, I would recommend alternative approaches:
- There are C# to C++ converters. They may help you to convert the 'algorithm' or 'control' parts of your code.
- For the graphical front end, ideally use Qt and QML, and re-implement (and improve on the way) your HMI.

Depending on the complexity of your application, porting this way may need some time but it is well worth the effort. 
Getting rid of C#/.NET altogether will improve performance and portability.

QNX has a strong Services department and could take on parts or possibly the entire porting of your application - I 
highly recommend reaching out to the QNX Sales representative for your location to discuss further.