The Fireye E300 Expansion Modules provide increased interlock supervision capability of the Flame-monitor control system. by wiring any of the 16 interlock switches into the Expansion Module (three additional recycling interlocks and 13 additional running safety interlocks), the Flame-Monitor will automatically act as a "first out" annunciator for these interlocks. The user can select the lockout message associated with each set of terminals of the E300 from a library of messages using the ED510 display module. The user ca also customize the lockout alarm messages (up to 40 characters in length) by using an IBM compatible PC, E300 software, EC485 converter, and ED512 cable. The Expansion Modules do not interfere with the normal operation of the Flame-Monitor system. It expands the diagnostic capability of the control, identifying the specific limit in the operating control circuit (LI-13) or running safety interlock circuits which causes the burner shutdown or lockout, reducing troubleshooting time and expense.