You are here: CSP Developer’s Guide: Overview > 4 EXS API Application Development > The Core Message Set
The Core Message Set is a subset of the API messages. When the CSP is shipped, it is not running system software. However, the Core Message Set is shipped on the CSP, residing in the firmware on the Matrix Controller card. The Core Message Set downloads system software from the host and queries the CSP.
When a valid download finishes, the CSP stops running the Core Message Set and starts running the System Software in RAM on the Matrix Controller card.
The following messages make up the Core Message Set:
• Alarm
• Become Active
• Card Status Query
• Clear System Software
• Download Begin BRecord
• Download Begin SRecord
• Download BRecord
• Download Complete
• Download SRecord
• Fault Log Query
• Poll
• Poll Interval Configure
• Poll Request
• Reset Matrix
• TFTP Manage
• Version Request