I'll respond here rather than to your post at the AD site as this may be more widely seen.
Your question is very nebulous. You need to define it more precisely for us to help.
1. The PLC has some sort of ASCII data. How did it get this ASCII data? Did it read it somewhere? How?
2. Somehow the PC must become aware of this data. We can discuss methods of doing this after the first question is defined.
3. Then the PC will use this data to initiate a printing cycle. Is the exchanged data the only thing printed or is the data just a pointer to a larger amount of data within the PC? Exactly what is being printed?
Let's get the answers to these questions.