You can prepare a simple text file with one text message on each line. Then you have two different options how to continue:
1) The PIRA32 RDS encoder will be placed on a remote site without online connection:
Use Dynamic PS 2 and Messages feature. Go to the Messages sheet and load your text file using the Load button. Then continue as described here:
http://www.pira.cz/rds/show.asp?art=guide_scheduling_0 (select Dynamic PS 2 instead of RT2). The RDS encoder will loop through the text messages automatically with no more support from the PC.
2) The RDS encoder will be permanently controlled from a PC:
Use Dynamic PS 1 and External text feature. Continue here:
http://www.pira.cz/rds/show.asp?art=guide_text_5. Make sure you've selected "All lines" option. The MagicRDS will read the text file line per line in a loop and send the text to the RDS encoder as Dynamic PS 1.
Complete guide for different cases is at
http://www.pira.cz/rds/show.asp?art=magic_rds_how_to