Control Mode - Hanna Instruments HI21 Series Instruction Manual

CONTROL MODE

RELAY MODES
The control mode is the normal operational mode for these
meters. During control mode HI21 and HI22 fulfill the fol-
lowing main tasks:
• convert information from pH/ORP and temperature inputs
to digital values;
• control relays and generate the analog outputs as deter-
mined by the setup configuration, display alarm condition;
• RS485 management (if the feature is included).
In addition, HI21 and HI22 can log working data through
RS485 connection. This data includes:
• pH, mV and C measured values;
o
• last calibration data;
• setup configuration (also from PC).
The status of the meter is shown by the LED's on the right
STATUS
Control Alarm Alarm LED (green) Relay LED (yellow) Red LED
OFF ---
ON OFF
ON ON
Meter exits control mode by pressing SETUP or CAL and
confirming the password. Note that this command generates
a temporary exit. To deactivate the
control mode definitively, set CON-
TROL ENABLE to "0" (item # 02).
Once enabled, the relays 1 and 2 can be used in four
different modes:
1) ON/OFF, high setpoint (acid dosage) (not for HI21523);
2) ON/OFF, low setpoint (base dosage) (not for HI21523);
3) Proportional or PID (HI21523 only), low setpoint (base
dosage, if available);
4) Proportional or PID (HI21523 only), high setpoint (acid
dosage, if available).
LEDs
ON OFF
ON ON or OFF
OFF ON or OFF
ON
OFF
Blinking
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