c. Press ENTER.
The display shows the sensor current.
d. Note the units
µA is microamps; na is nanoamps.
4. Change the decade box resistance and verify that the correct current is shown.
Calculate the current from the equation:
The voltage of a fresh 1.5 volt battery is about 1.6 volt (1600 mV).
8.4.11 Simulating inputs - pH
General information about simulating pH inputs
This section describes how to simulate a pH input into the transmitter. To simulate a pH
measurement, connect a standard millivolt source to the transmitter. If the transmitter is
working properly, it will accurately measure the input voltage and convert it to pH.
Although the general procedure is the same, the wiring details depend on whether the
preamplifier is in the sensor, a junction box, or the transmitter.
Preamplifier in transmitter
To simulate a pH input when the preamplifier is in the transmitter, complete the following
steps.
1. Turn off automatic temperature correction and set the manual temperature to 25 °C
(77 °F).
2. Disconnect the pH sensor. Also, disconnect the chlorine sensor anode lead. Connect
a jumper wire between the pH IN and REF IN terminals.
3. Confirm that the transmitter is reading the correct mV value.
a. With the main display showing, press DIAG.
b. Press NEXT until the display shows PH.
c. Press ENTER.
The display shows InpUt followed by a number. The number is the raw input
signal in millivolts. The measured voltage should be 0 mV.
4. Confirm that the transmitter is reading the correct pH value.
a. Go to the main display.
b. Press 3 or 5.
Diagnostics and troubleshooting
114 Rosemount 5081
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