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Troubleshooting
Table 12-2
I/O problems and remedies continued
Symptom
Constant mA output
mA output consistently out of
range
Consistently incorrect mA
measurement
mA reading correct at low
currents but wrong at higher
currents
Consistently incorrect
frequency measurement
Erratic frequency
measurement
Cannot zero with Zero
button (Model 1500/2500
transmitters only)
Cannot connect to terminals
33 & 34 in service port mode
(Model 1500/2500
transmitters only)
Cannot establish Modbus
communication on terminals
33 & 34 (Model 1500/2500
transmitters only)
Configuration and Use Manual
Possible cause
Non-zero HART address (multi-drop
communications) (primary mA output
only)
Output is fixed in a test mode
Burst mode enabled (primary mA
output only)
Zero calibration failure
Fault condition if fault indicator is set to
upscale or downscale
LRV and URV not set correctly
Output not trimmed correctly
Incorrect flow measurement unit
configured
Incorrect process variable configured
LRV and URV not set correctly
mA loop resistance may be too high
Output not scaled correctly
Incorrect flow measurement unit
configured
RF (radio frequency) interference from
environment
Not pressing Zero button for sufficient
interval
Core processor in fault mode
Terminals not in service port mode
Leads reversed
Transmitter installed on multidrop
network
Incorrect Modbus configuration
Leads reversed
Possible remedy
Set HART address to zero. See Section 12.19.
Exit output from test mode. See Section 5.3.
Disable burst mode.
Cycle power.
Stop flow and rezero. See Section 5.5.
Check the fault indicator settings to verify
whether or not the transmitter is in a fault
condition.
If a fault condition is present, see Section 12.7.
Check the LRV and URV. See Section 12.21.
Trim the output. See Section 5.4.
Verify flow measurement unit configuration. See
Section 12.20.
Verify process variable assigned to mA output.
Check the LRV and URV. See Section 12.21.
Verify mA output 1 or mA output 2 load
resistance is below maximum supported load
(see installation manual for your transmitter).
Check frequency output scale and method. See
Section 12.22. Verify voltage and resistance
match the frequency output load resistance
value chart (see your transmitter installation
manual).
Verify flow measurement unit configuration. See
Section 12.20.
See Section 12.14.4.
Button must be depressed for 0.5 seconds to be
recognized. Depress button until LED starts to
flash yellow, then release button.
Correct core processor faults and retry.
Terminals are accessible in service port mode
ONLY for a 10-second interval after power-up.
Cycle power and connect during this interval.
Switch leads and try again.
All Model 2500 devices on network default to
address=111 during 10-second service port
interval. Disconnect or power down other
devices, or use RS-485 communications.
After 10-second interval on power-up, the
transmitter switches to Modbus
communications. Default settings are:
• Address=1
• Baud rate=9600
• Parity=odd
Verify configuration. Default settings can be
changed using ProLink II v2.0 or higher.
Switch leads and try again.
133
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