Writing Text to STRING RSLOGIX 500

[paulrd42 0]

Sorry new to working with PLC's, 

I am trying to write text to a ST file on an RSLOGIX 500 machine, its for a LED display, I am just trying to update the screen to new texts, it all works I am just having trouble inputting the text properly into the string file. I would like to read about it if anyone can point me to a good document or manual that can explain what characters to use? 

I see many posts about using VBA using Excel work on RSLOGIX 500? But would like to know how to do it manually first. 

Thank you