MODEL 54e pH/ORP | SECTION 5.0 |
| SOFTWARE CONFIGURATION |
5.8
Alarms
Diagnostics
Auto Calibration
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"
ExitEnter 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
ExitEdit
Ref imp hi: 140 kΩ
Zero offset: 60 mV
Cal warn: 0%
ExitEdit
Zero offset; 60 mV Cal warn: 0% Imped comp: On
ExitEdit
2. | Menu Item | Option | Related Fault Messages |
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| Diagnostics | On/Off |
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| Glass impedance | ||
| high setpoint | (0 disables) |
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| Glass impedance | “Cracked glass | |
| low setpoint | (0 disables) | failure” |
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| Reference impedance | "High reference | |
| high setpoint | (0 disables) | imped" |
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| Zero offset | "Zero offset err" | |
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| (0 disables) |
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| Calibration recommended | "Calibration warning" | |
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| (0 disables) |
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| Imped comp | On/Off |
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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.
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