User Manual PolyGard
®
2 Sensors 2023-11 Page 21 | 40
6.5 Exchange of Sensor Head
Instead of the on-site calibration, the used Sensor can be simply and conveniently replaced by a
calibrated one.
6.5.1 Sensor SC2
The communication of the local bus (SC2 <> Board) is continuously monitored during
operation and results in an immediate error message on the Board in case of fault or
interruption. When exchanging the Sensor, communication is also interrupted which
leads to an immediate triggering of the error message.
• Disconnect the SC2 connector from the Board (error message will be activated).
• Loosen the locknut.
• Remove used SC2.
• Take calibrated SC2 out of the original packaging, check for gas type, measuring range and
valid calibration date.
• Insert the SC2 and tighten with locknut.
• Insert the SC2 plug into the socket at the Board. Check plug for proper engagement.
The local bus communication is automatically established and tested. At the same time, the gas type
and the measuring range of the "new" SC2 are compared with the data stored in the Board. If they
match and the communication is correct, the error message will be automatically acknowledged in
the Board.
The yellow LED of the Board is continuously lit as long as the SC2 connector is disconnected (com-
munication error). After the local bus communication has been re-established and the conformity
test has been successful, the Board stays in the error state until the Sensor’s warm-up time is over.
6.5.2 Sensor MC2
• Disconnect the used MC2 from the terminals.
• Loosen the lock nut.
• Remove the used MC2.
• Take calibrated MC2 out of the original packaging, check for gas type, measuring range and
valid calibration date.
• Insert MC2 and tighten with locknut.
• Connect the new MC2 to the terminals.
6.5.3 Perform Function Test
By applying a test gas, the Sensor is exposed to a defined gas concentration. The measurement signal
at the analog output, the relay outputs or the digital display must be checked for correctness.
This test checks the complete functional chain - Sensor Element > Sensor > Local Bus (SC2) or Analog
Output Signal (MC2) > Board > Field Bus > Evaluation Unit.
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