Fault Conditions And Selftest Procedures - Hanna Instruments HI21 Series Instruction Manual

FAULT CONDITIONS AND SELFTEST PROCEDURES

Note
52
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 op-
tion to perform a reset of EEPROM. Thus the reset can be
performed whenever needed. It may be useful to provide
a means to reset EEPROM directly (without a previous EE-
PROM error detection). This is done by pressing CFM first
and then SETUP ,  and CAL DATA simultaneously.
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 cer-
tain number of attempts (this can be due, for example, to
damage 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).