28 29
Clean and check the electrode.
• pH electrode broken or leakage (10) : The electrode
glass is broken or short circuits have been caused by moisture
or dirt.
Check pH probe and cable; replace them if necessary.
• Reference electrode broken or dirty (11) : The refer-
ence electrode is soiled or broken. Also the reference elec-
trode or the matching pin could not have been immersed
in the solution.
Clean the electrode and replace it when necessary.
• Old pH probe (12) : The pH probe is old (offset outside
of ±30 mV or slope outside the range 53.5 to 62 mV/pH).
The electrode is still working, but it is recommended to
clean or replace it.
• Dead pH probe (13) : Offset is outside of ±60 mV or
slope outside the range 40 to 70 mV/pH. Readings are not
reliable.
Try to clean the probe; if the error persists after cleaning,
replace the probe immediately.
• No calibration (14) : The device has lost its calibration
due to an EEPROM reset.
Calibrate again all the magnitudes.
• Temperature probe broken (20) : Check the tempera-
ture probe wires and connections.
Replace the probe if necessary.
• Cellular error (50) : This is an error related to the HI
504900 GSM module. Check the power supply for HI
504900. Verify that the signal coverage is good.
• Power reset (90) : The device was restarted due to a
power failure.
• EEPROM corruption (91) : The EEPROM data is dam-
aged. Reset the EEPROM, then recalibrate and reconfigure
completely the instrument.
• Watchdog reset (92) : The device was restarted due to a
watchdog reset or a manual reset done through the key-
board.
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).
