Detcon PI-700 0-500ppb - Manual (Page 26)

Model PI-700 0-500ppb
PI-700 0-500ppb Instruction Manual Rev. 0.0 Page 22 of 53
measurement mode. This feature also allows the user to log the AutoZero and AutoSpan events via their
master control system.
Sensor Life
Sensor Life is calculated after each AutoSpan calibration and is reported as an indicator of remaining service
life. It is reported in the “View Sensor Status” menu and as a RS-485 Modbus™ register bit. Sensor Life is
reported on a scale of 0-100%. When Sensor Life falls below 25%, the sensor cell should be cleaned or
replaced within a reasonable maintenance schedule.
Last AutoSpan Date
This reports the number of days that have elapsed since the last successful AutoSpan. This is reported in the
View Sensor Status menu. After 180 days, an AutoSpan Fault will be declared.
3.6.2 Fault Diagnostic/Failsafe Features
Fail-Safe/Fault Supervision
Model PI-700 sensors are designed for Fail-Safe operation. If any of the diagnostic faults listed below are
active, the ITM Display will scroll the message “Fault Detected” every 1 minute during normal operation. At
any time during “Fault Detected” mode, holding the programming magnet over PGM1 or PGM2 for 1 second
will display the active fault(s). All active faults are reported sequentially.
Most fault conditions result in failed operation of the sensor. In these cases the 4-20mA signal is dropped to
the universal fault level of 0mA. These include the AutoSpan Calibration faults, Sensor Fault, Processor Fault,
Memory Fault, Loop Fault, and Input Voltage Fault. The 0mA fault level is not employed for Temperature or
AutoSpan Faults. For every diagnostic fault condition the associated RS-485 Modbus™ fault register will be
flagged to alert the user digitally.
NOTE: Refer to the Troubleshooting Guide section for guidance on how to address fault
conditions.
Range Fault – AutoSpan
If the sensor fails the minimum signal change criteria (Section 3.4.2) during AutoSpan sequence, the “Range
Fault” will be declared. A “Range Fault” will cause a “Fault Detected” message to flash intermittently on the
ITM display and drop the 4-20mA output to 0mA. The Modbus™ fault register bit for Range Fault will be set
and will not clear until the fault condition has been cleared. The sensor should be considered ‘Out-of-Service’
until a successful AutoSpan calibration is performed.
Stability Fault - AutoSpan
If the sensor fails the signal stability criteria (Section 3.4.2) during AutoSpan sequence, the “Stability Fault”
will be declared. A “Stability Fault” will cause a “Fault Detected” message to flash intermittently on the ITM
display and drop the mA output to 0mA. The Modbus™ fault register bit for Stability Fault will be set and
will not clear until the fault condition has been cleared. The sensor should be considered as ‘Out-of-Service’
until a successful AutoSpan calibration is performed.
Clearing Fault - AutoSpan
If the sensor fails the signal stability criteria (Section 3.4.2) during AutoSpan sequence, the “Clearing Fault”
will be declared. A “Clearing Fault” will cause a “Fault Detected” message to flash intermittently on the ITM
display and drop the mA output to 0mA. The Modbus™ fault register bit for Clearing Fault will be set and