Vaisala HMP228 - Manual (Page 26)

HMP228
Operating Manual
M210282en-A
20
4. MAINTENANCE
4.1 Self-diagnostics
The HMP228 transmitter goes through a self-diagnostics procedure when the
power is switched on. If the procedure does not reveal any errors or faults, the
transmitter starts operating normally. If errors or faults are found, check first if
the moisture and temperature sensors are damaged. If they are intact, send the
transmitter to Vaisala for repairs. The error messages are listed in Appendix 3.
If any errors occur during operation, the error messages are output on the local
display if the transmitter displays measurements; if the menus are used, error
messages are not output. The LEDs indicate errors at all times. During opera-
tion, however, the error messages are not output automatically through the se-
rial interface. If there is any reason to doubt that there is something wrong
with the transmitter, use command ERRS:
ERRS
If there are no error messages, only a prompt is displayed:
>ERRS
>
When errors have occurred, the transmitter outputs the error code (see Appen-
dix 3 for all error messages):
>ERRS
E40 f ( all ) out of range
>
4.2 Reference measurements
Reference measurements are needed to verify whether the transmitter readings
are within specifications. This way the user can check if the transmitter needs
calibration or service.
Whatever the technique used, make sure that the reference instrument is at the
same temperature as the checked instrument in order to avoid errors caused by
temperature differences. The reference measurement should be made as close
to the checked sensor as possible and the readings should be read at the same
time, when possible.