Vaisala HMP230 User Manual download pdf (Page 72)

HMP230 SERIES

User's Guide M210225en-B

8. MAINTENANCE

8.1. 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.

The reference meter should preferably use the same technology as the instru-

ment checked, i.e. transmitters with capacitive sensors should be checked with

instruments using capacitive sensors. This minimizes the risk of errors caused

by different measurement techniques.

Whatever technique is used, make sure the reference instrument is at the same

temperature as the checked instrument in order to avoid errors caused by tem-

perature 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.

The best reference measurements are made in laboratories. If it is possible to

take the transmitter out of process or control system, make the reference

measurement in a laboratory where the conditions are stable.

8.2. Self-diagnostics

The HMP230 transmitters go 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

whether the humidity and temperature sensors are damaged. If they are intact,

send the transmitter to Vaisala or a Vaisala representative for repairs. The

error messages the transmitter outputs are listed in Appendix 5.

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 <cr>

If there are no error messages, only a prompt is displayed:

>ERRS <cr>

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Vaisala HMP230 User Manual Page 72