Hanna Instruments HI 23 Series Instruction Manual page 42

DISPLAY SELFTEST
KEYBOARD SELFTEST
42
A I2C failure is detected when the I2C transmission is not
acknowledged or a bus fault occurs for more than a certain
number of attempts (this can be due, for example, to dam-
age sustained by one of the ICs connected to I2C bus).
If so, the controller stops any tasks and displays a perpetual
sliding message "Serial bus error" (i.e. this is a fatal error).
If an invalid date is read from RTC, it is initialized back to the
default date and time (01/01/98 - 00:00).
You can use special setup codes, perform selftest procedures
for LCD, keyboard, EEPROM, relays and LEDs, watchdog.
The operation of these functions is outlined in the setup sec-
tion. The selftest procedures are described in detail in the
following subsections.
The display selftest procedure consists of lighting up all of the
display segments together. The Display test is announced by
a scrolling "Display test" message.
The segments are lit for a few seconds and then switched
off before exiting the selftest procedure.
The keyboard selftest procedure begins with the message "But-
ton test, press LCD, CAL and SETUP together to escape". The
LCD will then show only a colon.