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DEFINITIONS
DEVIATION
EEPROM
FAIL SAFE ALARM
GLP
HYSTERESIS
IN-LINE CLEANING
NIST
PID
POTENTIAL MATCHING PIN
PROPORTIONAL BAND Interval, measured in percentage of the input range, where
PWM
RAM
RTC
SETPOINT
SOLUTION COMPENSATION
THRESHOLD
TRIGGER
WATCHDOG
Same as proportional band, but expressed in units of the
controlled magnitude (e .g . 1pH, 50 mV) .
Electrically Erasable Programmable Read-only Memory
(permanent memory) .
Signaling of the alarm by de-energizing the alarm relay
instead of energizing it . That protects against power failures
and interruptions of the alarm relay external wires .
Good Laboratory Practice .
Interval that must be passed over by the controlled mag-
nitude in the opposite direction after having activated a
relay, before deactivating it, in order to avoid uninterrupted
activation/deactivation of the relay .
Automatic procedure to stop control, clean the electrode
and then activate control again .
National Institute of Standards and Technology .
Proportional Integrative Derivative control .
Pin for connection of the potential matching (or
grounding) steel bar, which must be immersed into the
measured fluid, and is used together with a differential input
to avoid damage of the reference electrode due to ground
loop current .
the proportional action spans from 0 to 100 % .
Pulse Width Modulation .
Random Access Memory (non-permanent memory) .
Real Time Clock .
Value at which the measurement needs to be controlled .
Technique for compensating the differences on the
pH of the solution under measurement when its temperature
varies .
Value above/below which a control or alarm relay is acti-
vated or deactivated .
An event or command that acts like a mechanical trigger
in initiating a process .
Mechanism for issuing a reset of the device in case it gets
stuck .
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