User Guide

42
CONTROL MODE
The control mode is the normal operational mode for this meter.
During control mode HI 504 fulfills the following main tasks:
• convert information from pH/ORP and temperature inputs
to digital values and show them on the display;
• control relays and generate the analog outputs as deter-
mined by the setup configuration;
• display alarm condition;
• perform cleaning actions according to the relays configuration;
• start and stop hold mode according to the programmed
control timing;
• RS485 management.
In addition, the meter can log working data through RS485
connection. These data include:
• pH, mV and
o
C measured values;
• last calibration data;
• setup configuration (also from a remote workstation);
• event data.
In a normal situation, during control mode, the green LED is
ON and the error LED (red) is OFF. The red LED is never
fixed ON and blinks only upon an error.
The green LED is associated to the alarm relay and is OFF if
the alarm is active.
To deactivate the control mode set CONTROL ENABLE to
“OFF” in setup menu (CONTROL (“CtrL”) group).
When measurements are in overflow, the upper or lower range
limit is shown on the LCD with blinking digits.
RELAY MODES
There are four relay options that can be configured through
the setup menu to perform different tasks.
Once enabled, relays 1 and 2 can be used in four modes:
1. setpoint 1 (Analog output #1 must be set to recorder, “rECO”);
2. setpoint 2 (Analog output #2 must be set to recorder, “rECO”);
3. simple cleaning;
4. hold mode.