• If the diagnostic message disappears, either the RTD return or RTD sense wire is
broken. To verify a broken wire, disconnect the leads and measure the resistance
between them. Installing the jumper completes the circuit, but bypasses the
three-wire function. The transmitter no longer corrects for changes in lead wire
resistance with temperature. replace the sensor as soon as possible.
• If the diagnostic message remains, go to Step 3.
3. The cable connecting the sensor to the transmitter may be too long. Test using a
sensor with a shorter cable.
• If shortening the cable eliminates the problem, move the transmitter closer to
the sensor. It may also be possible to increase diameter of the RTD wires. Consult
the factory for assistance.
• If the diagnostic message remains, go to Step 4.
4. Check the temperature of the transmitter. Simulate both temperature and pH. See
tEMP HI and tEMP LO (Steps B and C) for temperature simulation and Section 8.4.11
for pH simulation.
• IF the transmitter fails either simulation, the electronic board stack should be
replaced.
• If the transmitter passes the simulations, the transmitter is not in good
condition, and the sensor should be replaced.
InPUt WArn
InPUt WArn means that the input value or the calculated pH is outside the measurement
range. The measured pH is less than -2 or greather than 16.
Troubleshooting InPUt WArn
1. Check for miswires and open connections, particularly at TB-10. Open connections
can be caused by loose connections, poor spade crimps, or broken wires. Be sure to
check junction boxes for proper pass through of all wires.
• If correcting a wiring problem clears the message, the system is in good
condition.
• If the message is still showing, go to Step 2.
2. Check that the transmitter is working properly by simulating a pH input. See
Section 8.1.7.
• If the transmitter does not respond to simulated inputs, replace the board stack.
• If the transmitter performs satisfactorily and the preamplifier is located in a
remote junction box or in a sensor-mounted junction box, go to Step 3.
• If the transmitter performs properly and the preamplifier is located in the
transmitter, the sensor has failed and should be replaced.
3. The problem may lie with the remote preamplifier or with the cable connecting the
preamplifier and junction box to the transmitter.
a. Be sure all wires between the junction box and transmitter are connected.
b. Use Rosemount cable. Generic cable may not work.
• If the disagnostic message clears, the interconnecting cable was the problem.
Diagnostics and troubleshooting
64 Rosemount 5081
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