Appendix B Page 11 Loop Powered Indicator
As the Mode button is pressed the display will change to the next available unit in the order
shown above starting with the BU. With a BU of inH2O for example, the order would be
bar, kg/cm2, mA, %, psi, then back to inH2O.
2.3.4 Error Conditions
LPIs that have not been factory calibrated will alternately show a reading and UCUC (for
Uncalibrated) in the display for four seconds. Customers should never see this indication
unless the EEPROM has completely lost its contents.
The LPI reads an EPROM checksum every second and compares it to a checksum
calculated on the RAM area holding the data read from the EEPROM. If there is a
difference the EEPROM is reread and the checksums are tested again.
An invalid checksum causes a reset and reread, during which the display will show a
blinking EErr message. Reset occurs every 250 milliseconds.
If a write of the EEPROM (only occurs during configuration or calibration) fails because the
EEPROM did not acknowledge the write the same EErr message is displayed but is not
blinking because the LPI has been halted on the condition of the failure.
2.3.4.1 Conversion and Display Error Conditions
During operation three error conditions can occur that cause “dashes” to be displayed.
The first is a “cannot display” condition that can occur when the number to be shown is too
large to fit in the LCD display. This can occur, for example, if the Full-scale value was set
as 19,999 (equivalent to 20 mA). When the input current exceeds 20 mA a value of 20,000 or
larger cannot be displayed – in this case the display will show four dashes “----“.
The second and third conditions occur when the input current has exceeded the valid
conversion range and a numeric display value would be meaningless and possibly
misleading. If the current exceeds 21.6 mA to the point where internal conversions are not
valid the display will show two “dashes” right-justified in the display e.g., “ --“. If current
drops below 2.4 mA to the point where internal conversions are not valid then two left-
justified “dashes” are displayed e.g., “-- “.
2.4 SERVICE
Model 2808 Loop Powered Indicators are equipped with a 250 mA Quick Acting Fuse (F1)
that is situated on the Meter Motherboard Assembly. Check the following items if Loop
Powered Indicator operation is faulty:
1. Check wiring at TB1 of the Meter Motherboard.
2. Check field wiring at the field device.
3. Check Fuse F1 and replace it if it is defective (see Figure 2-2).
4. Make sure that the Meter Motherboard is properly secured to the transmitter.
5. Make sure that the Meter/Display Board is properly mated with the Meter Mother-
board.
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