Vaisala PTU300 - Rtest; Sensor Functions; Chemical Purge (Optional)

Chapter 4 ________________________________________________________________ Operation
VAISALA______________________________________________________________________ 139
RTEST
Use the serial line command RTEST to test the operation of the relays.
RTEST [x1 x2 x3 x4]<cr>
where
x
= ON/OFF
Example: Activate and then release all four relays.
>rtest on on on on
ON ON ON ON
>
>rtest off off off off
OFF OFF OFF OFF
>
Enter the command RTEST without parameters to stop testing.
Sensor Functions
Chemical Purge (Optional)
In some specific applications the sensor gain may decrease gradually due
to an interference caused by a particular chemical present in the
measured gas, for example. The decrease of sensor gain due to an
interfering chemical and the effect of the chemical purge process are
illustrated below, see Figure 63 on page 140. The sensor polymer absorbs
the interfering chemical; and this reduces the ability of the polymer to
absorb water molecules and consequently the sensor gain decreases. In
chemical purge, heating the humidity sensor to a temperature level of
approximately +160 °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 the transmitter returns to
normal mode. The whole cycle takes about 6 minutes.
NOTE
Chemical purge function locks the output values for about 6 minutes.