air the h 2 sensor 78 generates a signal 94 which is representative of the h 2 content in the environment detected thereby it may also include bit for the testing of proper operation thereof integral heaters and temperature sensors within both the co and h 2 sensors 76 and 78 respectively stabilize their performance over the operating temperature and humidity ranges and permit self testing thereof for a more detailed description of such mems based chemical sensors reference is made to the co pending patent application bearing ser no 09 940 408 filed on aug 27 2001 and entitled u201c a method of self testing a semiconductor chemical gas sensor including an embedded temperature sensor u201d which is incorporated by reference herein this application is assigned to rosemount aerospace inc which is the same assignee and or a wholly owned subsidiary of the parent company of the assignee of the instant application each fire detector also includes fire detector electronics 100 which may comprise solid state components to increase reliability and reduce power consumption size and weight the heart of the electronics section 100 for the present embodiment is a single chip highly integrated conventional 8 bit microcontroller 102 for example and includes a can bus controller 104 a programmable read only memory rom a random access memory ram multiple timers all not.