Figure 6.3 Slew rate damping
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 relect
the actual state of the measurement.
The measurement hold takes place after the CALC value and ield corrections have
been calculated but before the signal iltering (damping) takes place (see Section 6.4).
If the hold is on, the output ilter 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 conigured 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 EXTERNAL
HOLD will be shown.
6.2.2 Hold during wash
When the setting "Hold during wash" (see Section 6.5.2) is conigured ACTIVE, the out-
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.
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