Hanna Instruments HI 21 Series - Manual (Page 3)

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• Temperature compensation of the pH reading (for HI 21
series only).
• Manual temperature setting when the temperature probe is
not inserted or temperature exceeds the upper range.
• Internally recorded last calibration data (non-volatile EE-
PROM memory): calibration date and time, pH offset, pH
slopes, number of calibration points and correspondent
pH values (for HI 21 series only) or calibration date and
time and the mV calibration points used (for HI 22 series
only).
• Input: pH electrode with BNC connector.
• ±5 Vdc output for amplified electrodes (max 10 mA).
• Output:
- isolated 0-1 mA, 10 K maximum load (optional);
- isolated 0-20 mA, 750 maximum load (optional);
- isolated 4-20 mA, 750 maximum load (optional);
- isolated 0-5 Vdc, 1 K minimum load (optional);
- isolated 1-5 Vdc, 1 K minimum load (optional);
- isolated 0-10 Vdc, 1 K minimum load (optional).
• Real time clock.
PRELIMINARY EXAMINATION
Remove the instrument from the packing material and exam-
ine it carefully to make sure that no damage has occurred
during shipping. If there is any noticeable damage, notify
your Dealer or the nearest Hanna Customer Service Center
immediately.
Note Save all packing materials until you are sure that the instru-
ment functions correctly. Any damaged or defective items must
be returned in their original packing materials together with
the supplied accessories.
GENERAL DESCRIPTION
The product is a real time microprocessor-based pH/ORP
controller. It provides accurate measurements, flexible
ON/OFF, proportional or PID control capabilities and dual
alarm signals.
The system is composed of a case inside which the signal
conversion circuitry, the microprocessor circuitry and the
output power drivers are contained.
MAIN FEATURES OF DIFFERENT MODELS
• Display: large LCD with 4 ½ 13 mm digits and 3 ½ 7.7
mm digits.
• LEDs: three (HI 22) or four (HI 21) LEDs are provided for
signaling the energizing of relay 1 (a yellow LED), relay 2
(a yellow LED in HI 21 Series only) and alarm relays (a
green and a red LED).
• Relays: Electromechanical type, working through NO,
COM and NC contacts; 1 or 2 output relays for acid or
base dosage; 1 output relay for alarm condition.
• RS485 isolated communication link.
• Calibration and Setup procedures allowed only through
an unlock password.
• Calibration: for HI 21 series at 1, 2 or 3 points with pH
4.01, 7.01 and 10.01 buffers; for HI 22 series in 1 or 2
points at 0, 350 and 1900 mV.
• Temperature compensation of the HANNA standard buff-
ers (for HI 21 series only).