Emerson 54e pH/ORP instruction manual Diagnostic Variables

MODEL 54e pH/ORP	SECTION 8.0
	TROUBLESHOOTING

8.1 DISPLAYING DIAGNOSTIC VARIABLES

This section explains how these helpful diagnostics can be viewed:

1.Electrode input in mV: Used to check if the signal produced by the sensor is within acceptable limits (see Figure 8-1 for typical sensor mV response at 25°C).

2.Glass impedance in MΩ: Used to check integrity of glass electrode. Broken glass membranes will have low impedance.

3.Reference impedance in kΩ: Used to indicate how coated the ref- erence electrode has become. Coated or plugged sensors will have high values of reference impedance.

4.Zero offset in mV: Indicates the deviation from the typical sensor response (Figure 8-1) as of the last buffer calibration. The controller compares the value at 7 pH with the ideal value of zero mV at 7 pH.

5.Slope in mV/pH: Indicates the sensitivity of the glass electrode. This number tends to drop as a sensor ages. Values below 47 are con- sidered too low for calibration.

6.Software version

Calibrate

Diagnostic Variables

Program

Use the following procedure :

1.From the main display, press any key.

2.With the down arrow key, move the cursor down to "Diagnostic Variables" and then press Enter (F4).

Exit

Input: 120 mV

Glass imped: 300 MΩ

Ref imped: 8 kΩ

Exit

Zero offset: 0 mV

pH slope: 59.02 mV/pH

Version: pH1.01

3.Diagnostic variables are displayed three at a time. More variables are viewable until the cursor (showing highlighted text) is brought down to the bottom line.

Use the down arrow key to view the items on the lower screen.

The up arrow key can be used to return to a previously viewed item .

Press the Exit (F1) key to return to the main menu above.

NOTE

Many diagnostic variables can be read directly on the main dis- play in the lower left or lower right positions. For details, see Section 5.5.

Exit

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