Vaisala HMT310 - Manual (Page 54)

USER'S GUIDE____________________________________________________________________
54 __________________________________________________________________ M210619EN-D
AERR Set Error Outputs
Syntax: AERR
Factory default state for analog outputs during error condition is 0 mA.
Please be careful when selecting the new error value, the error state of
the transmitter should not cause problems in process monitoring.
Example:
>aerr
Ch1 error out : 0.000mA ?
Ch2 error out : 0.000mA ?
NOTE Error output value needs to be within a valid range for output type.
NOTE The error output value is shown only when there are minor electrical
faults such as a humidity sensor open circuit. When there is a severe
device malfunction, like analog output electronics failure or
microprocessor ROM/RAM failure, the error output value is not
necessarily shown.
Chemical Purge (Optional)
General
In some specific applications the sensor gain may decrease gradually due
to an interference caused by some particular chemical present in the
ambient (see Figure 16 on page 55). The sensor polymer absorbs the
interfering chemical; this reduces the ability of the polymer to absorb
water molecules and so decreases the sensor gain. In chemical purge
heating the humidity sensor to a temperature level of approximately
+180 °C for several minutes evaporates the interfering chemical.
The purge function starts with heating stage, continues with settling and
when the temperature of the sensor is decreased transmitter returns to
normal mode. The whole cycle takes about 8 minutes.
NOTE Chemical purge function locks the output values for about 8 minutes.