User Guide

MEASURE MODE

The measure mode is the normal mode for the instrument.

During measure mode, pH and temperature or ORP mea-

surements are acquired and sent to HI 504 or to a PC with

HI 92500 or another software implementing the communi-

cation protocol described in this manual (see the “RS485

communication section”).

In a normal situation, during measure mode the green LED is

ON and the red LED is OFF (LEDs are located inside the

instrument case).

When the Setup mode or the Calibration mode are entered

through the HI 504920 (or through the HI 504910 inter-

nal keyboard), both the green and the red LEDs are ON.

The red LED ON warns the user that the HI 504910 is not

measuring and transmitting measurements.

Note In this situation, an HI 504 connected to HI 504910 will

be in hold mode.

In case of an error occurs in HI 504910, the green LED

turns OFF and the red LED flashes.

Note When measurements are in overflow, the internal LCD of the

HI 504910 or that of HI 504920 (in terminal mode) will

show the blinking upper or lower boundary value.

ERRORS

When an error occurs, the green LED turns OFF and an

alarm indication is given by the flashing red LED.

Below are listed all the errors with the correspondent error

code.

The error code is reported in the event log file, which can be

examined by means of the DISPLAY key while in normal mea-

sure mode (see the “Event log file scrolling” section). This is

necessary for identifying which error is active and makes the

red LED flash.

• Life check error (03) : The pH reading did not vary more

than ±0.10 pH (for pH) or the mV reading did not vary

more than ±10 mV within the time selected through the

“Life check time” setup item (I.11).