Hanna Instruments HI 21 Series - Manual (Page 9)

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CONTROL MODE
The control mode is the normal operational mode for these
meters. During control mode HI 21 and HI 22 fulfill the
following 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, HI 21 and HI 22 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 con-
firming the password. Note that this command generates a
temporary exit. To deactivate the
control mode definitively, set
CONTROL ENABLE to “0” (item
# 02).
RELAY MODES
Once enabled, the relays 1 and 2 can be used in four differ-
ent modes:
1) ON/OFF, high setpoint (acid dosage) (not for HI 21523);
2) ON/OFF, low setpoint (base dosage) (not for HI 21523);
3) Proportional or PID (HI 21523 only), low setpoint (base
dosage, if available);
4) Proportional or PID (HI 21523 only), high setpoint (acid
If M1 = 2 and M2 = 3
then S1+H1LA, HA>S2+D2;
If M1 = 4 and M2 = 1
then S1LA, HA>S2;
If M1 = 1 and M2 = 4
then S1–H1>S2, S2–D2>LA, HA>S1;
If M1 = 3 and M2 = 4
then S1>S2, S2–D2>LA, HA>S1+D1;
If M1 = 4 and M2 = 3
then S2>S1, S1–D1>LA, HA>S2+D2;
For HI 21523 only:
If M1 = 1 then S1+D1If M1 = 2 then S1–D1>LA;
where the minimum deviation (D1 or D2) is 0.5 pH (for HI
21) or 25 mV (for HI 22).
Note The password cannot be viewed when SETUP is pressed with-
out entering the original password first. The default password
is set at “0000”. In the event that the user forgets the pass-
word, this can be reset to “0000” by pressing and holding
CFM and then pressing LCD and CAL DATA at the same time
when the pH controller is in normal operating mode (idle or
control with measurement displaying).
Note When a wrong setup value is con-
firmed, the pH controller does not skip
to the next setup item but remains in
the current item displaying a flashing
“WRONG” indicator until the param-
eter value is changed by the user (the same is also true for
the setup code selection). In some circumstances, the user
cannot succeed in setting a parameter to a desired value if
the related parameters are not changed beforehand; e.g. to
set a pH high setpoint to 10.00 the high alarm must be set to
a value greater than pH 10.00 first.
Note For code numbers 40, 41, 42, the output is related to pH or mV units
depending on the model (pH process meters or mV process meters).
Items 41 and 42 are not available in HI 215YZ .