Emerson Rosemount FCL, Reference Manual

Page: 103 / 108

9.9 Simulate pH input
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.
Procedure
1. Set automatic temperature correction to Manual and set manual temperature to 25
°C.
2. Turn off solution and temperature correction.
See Configuring temperature related settings .
3. Disconnect the sensor and jumper wire between the IN REFERENCE and IN pH
terminals.
4. Press
DIAG
and choose sensor 2 (pH).
The input voltage should be 0 mV, and the pH should be 7.00. Because calibration
data stored in the transmitter may be offsetting the input voltage, the displayed pH
may not be exactly 7.00.
5. If a standard millivolt source is available, disconnect the jumper wire between IN
REFERENCE and IN pH and connect the voltage source as shown in Figure 9-3 .
Figure 9-3: Simulating pH input
Be sure to jumper the IN REFERENCE and GND SOL terminals.
6. Calibrate the transmitter using the procedure in Procedure - manual calibration .
Use 0.0 mV for Buffer 1 (pH 7.00) and -177.4 mV for Buffer 2 (pH 10.00).
If the transmitter is working properly, it should accept the calibration. The slope
should be 59.16 mV/pH, and the offset should be zero.
7. To check linearity, return to the main display and the pH/temperature/mV screen.
Set the voltage source to the value shown in the table and verify that the pH and
millivolt readings match the values in the table.
Voltage (mV) pH (at 25 °C)
295.8 2.00
177.5 4.00
59.2 6.00
-59.2 8.00
-177.5 10.00
-295.8 12.00
Reference Manual Troubleshoot
00809-0100-3412 May 2019
Rosemount FCL 1056 103