Even only text data enables POS printer to print, while the modification characters, changing configurations or specific functions need to be sent with each command.
Refer to the command reference because each a command depends on a printer type.

Each the command reference is available from the below web site. Command references of some models are included with the instructions.
http://www.citizen-systems.co.jp/english/support/download/printer/document/command/index.html

Command references lists easy sample programs as instructions on the use of the command.
Contact us if it's not clear.
(It may not be possible to support to develop an application.)