10.4.1 Perform loop tests using the display
A loop test is a way to verify that the transmitter and the remote device are
communicating properly. A loop test also helps you know whether you need to trim mA
outputs.
Prerequisites
Before performing a loop test, configure the channels for the transmitter inputs and
outputs that will be used in your application.
Follow appropriate procedures to ensure that loop testing will not interfere with existing
measurement and control loops.
Procedure
1. Test the mA output(s).
a. Choose OFFLINE MAINT > SIM > AO1 SIM or OFFLINE MAINT > SIM > AO2 SIM, and
select a low value, e.g., 4 mA.
Dots traverse the display while the output is fixed.
b. Read the mA current at the receiving device and compare it to the transmitter
output.
The readings do not need to match exactly. If the values are slightly different,
you can correct the discrepancy by trimming the output.
c. At the transmitter, activate Select.
d. Scroll to and select a high value, e.g., 20 mA.
Dots traverse the display while the output is fixed.
e. Read the mA current at the receiving device and compare it to the transmitter
output.
The readings do not need to match exactly. If the values are slightly different,
you can correct the discrepancy by trimming the output.
f. At the transmitter, activate Select.
2. Test the discrete output(s).
a. Choose OFFLINE MAINT > SIM > DO SIM, and select SET ON.
Dots traverse the display while the output is fixed.
b. Verify the signal at the receiving device.
c. At the transmitter, activate Select.
d. Scroll to and select SET OFF.
e. Verify the signal at the receiving device.
Troubleshooting
136 Micro Motion
®
Fork Density Meters (FDM)
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