During normal operation, the SONARtrac firmware will ping the preamplifier located within the sensor head cover for diagnostic information such as hardware and software numbers, and diagnostic voltages and temperatures. This will occur about every 10 seconds. If the transmitter cannot communicate with the preamp, the diagnostic values seen in SYSINFO file, and / or within the INFO screen of the transmitter menu, will not be available. If there are no other system failures the SONARtrac may continue to provide a valid flow reading; however, DIAGNOSTIC operations such as SENSOR CHECK or GAIN adjustment will not be possible. (As noted in the installation manual any failure during SENSOR CHECK should be confirmed by repeating the test to verify that the failure duplicates).