How to make php send commands to an Elgin l42 in BPLA language?

I need to do label impressions (with data generated by a web app in php) on an Elgin l42 (this printer model only). Could someone instruct me to solve my problem? I know there is a way via shell_exec, but I have no idea how to make it work. Not much material is found on this model on the internet. Thanks for the help.