Control Mode - Hanna Instruments HI700 Series Instruction Manual

CONTROL MODE

RELAY MODES
ON/OFF CONTROL MODE
18
The control mode is the normal operational mode for these meters. During control mode
the meter fulfills the following main tasks:
• converts information from EC/TDS and temperature inputs to digital values;
• controls relays and generates the analog outputs as determined by the setup con-
figuration, displays alarm condition;
In HI710 models it is possible to switch between EC and TDS reading pressing "LCD".
The TDS value is obtained multiplying the EC measurement by the TDS factor set through
setup. The HI700 models display EC only.
The status of the meter is shown by the LED's on the right.
STATUS
Control Alarm
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 CONTROL ENABLE to "0" (item # 02).
Once enabled, the relays 1 and 2 can be used in four
different modes:
1) ON/OFF, high setpoint (low conductivity dosage);
2) ON/OFF, low setpoint (high conductivity dosage);
3) PID, low setpoint (low conductivity dosage);
4) PID, high setpoint (high conductivity dosage).
An upper boundary is imposed for dosage time when relays are energized continuously,
i.e. when relay works in
ON/OFF mode or also in PID mode but in the latter case only if the relay is always ON. This
parameter can be set through setup procedure. When the maximum boundary is reached,
an alarm is generated; device stays in alarm condition until relay is de-energized.
Either for mode 1 or 2 (high or low conductivity dosage) the user has to define the
following values through setup:
• relay setpoint (µS/mS/ppm value);
• relay hysteresis (µS/mS/ppm value).
LEDs
Alarm LED (green) Relay LED (yellow) Red LED
ON OFF
ON ON or OFF
OFF ON or OFF
ON
OFF
Blinking