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MODEL 54e pH/ORP SECTION 5.0
SOFTWARE CONFIGURATION
5.8 ON-LINE DIAGNOSTICS SETUP
2. Menu Item Option Related Fault Messages
Diagnostics On/Off
Glass impedance 1-2000 MΩ “Aged glass warning”
high setpoint (0 disables)
Glass impedance 1-900 MΩ “Cracked glass
low setpoint (0 disables) failure”
Reference impedance 1-140 kΩ "High reference
high setpoint (0 disables) imped"
Zero offset 1-999 mV "Zero offset err"
(0 disables)
Calibration recommended 1-500% "Calibration warning"
(0 disables)
Imped comp On/Off
The values now being used by the controller are displayed. To change
any of these items, use the arrow key to highlight the desired item and
press Edit(F4). Use the arrow keys to make the change and press
Save(F4) to enter the change into memory.
"Glass Imp hi" warns of a glass electrode that may have exceeded it's
useful life. This warning level should be set higher than the new sensor's
impedance. For example, for a new sensor with a glass impedance of 150
MΩ, a setting of 400 MΩ may be appropriate.
"Glass Imp lo" warns of a broken glass electrode. This warning level
should be set lower than the new sensor's impedance. A good typical set-
ting would be 20 MΩ.
"Ref imp hi" warns of a coated sensor. This warning level should be set
higher than the new sensor's reference impedance. Sensors may have
reference impedance values that vary considerably, so it is a good idea
to check each new sensor before setting this value.
"Zero offset" indicates how far the millivolt response of the sensor is from
the ideal case. It is updated after buffer calibration and standardization. If
a calibration results in a large enough offset, the fault message will be dis-
played.
This section describes the options available for configuration of the on-
line sensor diagnostics. The controller checks the integrity of the glass
electrode (for pH only) and the reference electrode by continuously meas-
uring the impedance of each. The original controller configuration is with
diagnostic messages turned off. To enable this feature, see below.
1. Beginning from the main menu, move the cursor down to "Program"
and press Enter (F4). From the program menu, move the cursor down
using the arrow key to highlight "Configure" and press Enter (F4).
Use the arrow key again to highlight "Diagnostics" (as shown on the
left) and press Enter (F4).
Diagnostics: Off
Glass imp hi: 1000 MΩ
Glass imp lo: 20 MΩ
Exit Edit
Ref imp hi: 140 kΩ
Zero offset: 60 mV
Cal warn: 0%
Exit Edit
Alarms
Diagnostics
Auto Calibration
Exit Enter
Zero offset; 60 mV
Cal warn: 0%
Imped comp: On
Exit Edit