17
CONTROL MODE
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
o
C measured values;
• last calibration data;
• setup configuration (also from PC).
The status of the meter is shown by the LED’s on the right
STATUS
LEDs
Control
Alarm
Alarm LED (green) Relay LED (yellow) Red LED
OFF
---
ON
OFF
ON
ON
OFF
ON
ON or OFF
OFF
ON
ON
OFF
ON or OFF
Blinking
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).
RELAY MODES
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).
