Honeywell STT25D, Operator'S Manual

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Smart Temperature Transmitter STT250 – Operator Manual 29
6.4 Diagnostic and Troubleshooting
6.4.1 Analog Meter
The Analog Meter is an irreparable item. If it reads at the bottom of the scale with a
known input, check that the connections are good and that the voltage across the
meter/diode terminals is 0.5 to 0.7 V. This reading confirms that the delicate moving
coil connections have been damaged and that the meter should be replaced.
6.4.2 Smart Meter
Every time power is cycled to the transmitter/meter combination, the Smart Meter runs
a self test to check internal operations and switches on all display segments as shown
in Figure 15 for up to 10 seconds. This enables confirmation of their operation.
DIGITAL READOUT
(-19990 to +19990)
17-SEGMENT BARGRAPH
(0 to 100%)
ENGINEERING UNIT
INDICATOR
PUSH BUTTON LOCATION
STATUS MESSAGE
Figure 15: Horizontal Style Bargraph
6.4.2.1 Failed self test
If the self test fails, the display will go blank (i.e. revert to the unpowered display
showing only the basic bargraph outline). Note that some of the temporarily switched
on segments should only be seen with an STT250 in this initial self check e.g. "
K " for
a 1,000 engineering unit multiplier (only for readings over 20,000), " GPH ", " GPM ",
" mmHg " , " PSI ", " % ", " FLOW " and " inH
2
0 " (only used for flow and pressure
transmitters).
ANALOG " is switched on the LCD if the transmitter output signal is 4-20 mA analog.
The "Normal" display should have a partially switched on bargraph corresponding to
the transmitter % of span output signal and the corresponding digital display in % of
the selected units.