RoryLDM, I wonder if you would like the possibility to write your own CODESYS driver for the Beaglebone PRU?
There is the CODESYS Forge, where there is an open source community for CODESYS. Here you will find both documentation on how to develop your own drivers, as well as access to people that are happy to collaborate with you on such a project.
You can either go to forge.codesys.com and browse for Device drivers, or I have the link directly to your interest.https://forge.codesys.com/drv/wiki/Home/
Also, clearly this invitation is not limited to Rory, should others be reading this post and wish to help.