External Hold; Hold During Wash - Vaisala K-PATENTS PR-23 Series Instruction Manual

6 Configuration and calibration
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1. By using an external hold switch (see Section 6.3.2)
2. During prism wash (see Section 6.5.2)
3. For a preprogrammed time when there is an intermittent loss of sample on the
prism (due to voids in the process)
When the measurement result is in hold, the displayed concentration value and mA
output do not change. The diagnostic values (e.g. nD) shown on-screen always reflect
the actual state of the measurement.
The measurement hold takes place after the CALC value and field corrections have
been calculated but before the signal filtering (damping) takes place (see Section 6.4).
If the hold is on, the output filter remains in its earlier state, and the output signal is
stationary. If the hold is started when there is no output signal (e.g. no sample on the
prism), there will be no measurement signal during the hold.

6.2.1 External hold

When a switch input is configured for external hold functionality (see Section 6.3.2),
and the switch contact is closed, the measurement result is in hold. The measurement
result is kept in hold until the switch contact is opened. A status message
will be shown.
HOLD

6.2.2 Hold during wash

When the setting "Hold during wash" (see Section 6.5.2) is configured
put signal is in hold when the instrument is washing. The signal will be in hold during
all three phases (preconditioning, wash, recovery) of the wash process.
This setting can be used to avoid dips in the measurement signal during the prism
wash.
0.5 /s
0.2 /s
0.05 /s
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Time [s]
Figure 6.3 Slew rate damping
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ACTIVE
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EXTERNAL
, the out-