OLCT 700/710 TP
OLCT 700/710 TP Instruction Manual Rev. C.1 Page 33 of 45
Nuisance Alarms
• Check condulet for accumulated water and abnormal corrosion on terminal blocks.
• If nuisance alarms are happening at night, suspect condensation in condulet. Add or replace
Oldham’s Condensation Prevention Packet PN DET-960-202200-000.
• Investigate the presence of other target gases that are causing cross-interference signals.
• Determine if cause is RFI induced.
Processor and/or Memory Faults
• Recycle power in attempt to clear problem
• Restore Factory Defaults - This will clear the processor’s memory and may correct
problem.Remember to re-enter all customer settings for range and cal gas level after Restore
Factory Defaults.
• If problem persists, replace the Intelligent Transmitter Module.
Unreadable Display
• If due to excessive sunlight, install a sunshade to reduce glare.
Nothing Displayed – Transmitter not Responding
• Verify condulet has no accumulated water or abnormal corrosion.
• Verify required DC power is applied to correct terminals.
• Swap with a known-good ITM to determine if ITM is faulty.
Faulty 4-20mA Output
If Detector has a normal reading with no Faults displayed, and the 4-20 mA signal output is 0mA.
• Check that wiring is properly connected at terminal blocks and through to controller inputs. The 4-
20mA output loop must be closed to avoid a Loop Fault. If the 4-20mA output is not being used
the green wire from the detector must be connected to the (-) terminal on the Transient Protection
Module to ensure that it does not create a 4-20mA Fault (section 0).
• Perform a “Signal Output Check” sequence via Section 3.5.7 and verify 4-20mA output with
Current Meter.
• Swap with new ITM to determine if the ITM’s 4-20mA output circuit is faulty.
• If the 4-20mA current loop is still out of tolerance, contact Oldham’s Technical Support at
support@oldhamgas.com.
No Communication - RS-485 Modbus™
If detector has a normal reading with no Faults displayed and the Modbus™ is not communicating.
• Verify that the correct (and non-duplicated) serial address is entered (per Section 0).
• Check that the wiring is properly connected at terminal blocks, and the serial loop is wired
correctly.
• Perform a “Signal Output Check” per Section 3.5.7 and troubleshoot wiring.
• Consider adding a Modbus™ repeater if the distance from the nearest distribution drop is
excessive.
• Swap with new ITM to determine if the ITM’s serial output circuit is faulty.
• Refer to Oldham’s “Guide to Proper Modbus™ Communications” Application Note.
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