A windows based application was written for client, it interfaces to external circuitry via the LPT / Parallel Port. Making changes to the application would require the software be connected to this circuitry, which is fine when on site, but difficult when not.
I came up with an idea to use an arduino to simulate the signals on the LPT port which the windows application uses. After a bit of prototyping, trial and error, the final product was assembled.