Hanna Instruments HI 9914 - Manual (Page 8)

15 14
External fill button connection
• Connect the button
between FILL and IN-
PUT COMMON pins.
• The tank will be im-
mediately filled with
water if the external
fill button is pressed
and the water level is
below the normal level
float.
External FEED OK connection
This output is a current source from the FEED OK pin.
• Connect a LED, buzzer or other
device between FEED OK and IN-
PUT COMMON pins.
• When the water composition is good
for irrigation, the FEED OK will
source about 15mA and activate
the device.
Analog output connections
• Connect an external device between the
EC+ and EC- (for Conductivity signal) or
pH+ and pH- (for pH signal) pins.
• The output voltage is related to the value displayed on LCD. For EC the
output will be 0V for 0.00 on LCD and 5V for 10.00 on LCD; for pH the
output will be 0V for 0.00 on LCD and 7V for 14.00 on LCD.
Note: Never connect “EC” with “pH”. Make sure there is no galvanic
connection between the EC and the pH analog outputs, otherwise
the measured values will be not reliable and probes can be
damaged.
Relay connections
The controller is provided with six relay outputs (2A, 220V) protected by
2A fuses.
When a relay is off the
COMMON pin is connected with the NC pin; when
is on the COMMON pin is connected with the NO pin.
The NC pin is not accessible for the pH and EC pumps and the COMMON
• Place the low-level sensor to indicate the minimum water level for the
correct function of both the circulation and feeding pumps.
• Connect the sensor between INPUT COMMON and LOW LEVEL pins.
• Place the normal-level sensor to indicate the filling level when the tank
is full.
• Connect the sensor between INPUT COMMON and NORMAL LEVEL pins.
• Place the alarm-level sensor to limit the highest water level.
• Connect the sensor between
INPUT COMMON and HIGH (ALARM) LEVEL
pins.
Note: The level sensors act correctly if the sensor switch is closed when the
water is above the corresponding level
Irrigation start connection
Connect the irrigation-start switch
between
INPUT COMMON and IR-
RIGATION START pins.
Irrigation can be controlled by:
• using a switch connected between the INPUT COMMON and IRRIGA-
TION START: the irrigation is started by closing the switch, and lasts
until the contact is open.
• using a 5V-logic signal, connected to the IRRIGATION START and
referred to INPUT COMMON: the irrigation starts at level “0” (0V)
and stops at level “1” (5V).
• using a level sensor that will be open when the desired level is
reached: the controller will irrigate until the desired level is reached,
and the irrigation will restart if the water falls below this level.