At its basic level, any EDI form is just a text file; if you want to take the time to do them, you can do them in any text editor, although it’s not particularly efficient.
Your question leaves out a lot of information. Is it your requirement that you send out PO acknowledgments? Or is it the requirement of your customer? Are you talking about one PO a day, or several hundred? Are you set up to receive EDI transmissions? Or is this a new system you’ve been asked to set up? Does your internal account software have a way of outputting a customized file (or EDI files)?