Script to convert various .psd files in one PDF

Hello dear people,

I'm trying to convert various .psd files in a route into one pdf.

I have various .psd files in the route J:\My Documents\My Company\Posters

and I want to merge all this pdf files in just one pdf.

I tried to make it with an Action:

1. Opening the psd files in the folder

2. File>Automate>PDF Presentation (Select "Add Open Files" option)

3. And then save the PDF into any location

It could be a  very good way, but the problems is that I'll always have a different amount of psd files in this folder.

for example, in the moment I create the Action, the "Posters" folder contain 8 psd files and it will work very well, but for a next occasion the folder can contain 13 psd files, in this case if I exceute de Action I created, the action will convert in PDF only the first 8 files no the 13 files.

How I can achieve it?

I hope you can understand my issue and help me with a solution.

Thank you so much!