Fault Conditions And Selftest Procedures - Hanna Instruments HI 22 Series Instruction Manual

FAULT CONDITIONS AND SELFTEST PROCEDURES

The fault conditions below may be detected by the software:
• EEPROM data error;
• I2C internal bus failure;
• code dead loop.
EEPROM data error can be detected through EEPROM test
procedure at start-up or when explicitly requested using setup
menu.
When an EEPROM error is detected, user is given the option
to perform a reset of EEPROM. Thus the reset can be per-
formed whenever needed. It may be useful to provide a means
to reset EEPROM directly (without a previous EEPROM error
detection). This is done by pressing CFM first and then SETUP ,
and CAL DATA simultaneously.
Note
When an EEPROM reset has been per-
formed calibration data are reset to
default. An intermittent CAL will blink
on the display to advise the user of
this status.
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).
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The error detection for dead loops is performed by watchdog
(see below).
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.
DISPLAY SELFTEST
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.
KEYBOARD SELFTEST
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.
As soon as one or more keys are pressed, the appropriate
segments out of 88:88 corresponding to the pressed keys,
will light up on the screen.
For example, if LCD and
look like this:
are pressed together the LCD will
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