Self-Test / Functional State; General Detector Functions; Alarm Algorithms - Siemens Cerberus DLO1191 Manual

3.7.4

Self-test / functional state

3.8

General detector functions

3.8.1

Alarm algorithms

Siemens Building T echnologies
Cerberus Division
Periodically or on request by the control unit a comprehensive detector self-test is initi-
ated which monitors the signal amplifier and the EEPROM.
Also periodically monitored are the compensation value, line voltage, etc. The entire sig-
nal path is monitored with the compensation value. If the compensation value is too high
or too low, a corresponding signal is generated.
If the detector signals status changes, the control unit is able to read out the cause from
the detector memory.
«Functional state 0» corresponds to «Normal state»
«Functional state 1» corresponds to «Information»
e.g. thermal turbulence, repeated interruption of the beam, condensation
«Functional state 2» corresponds to «Impairment»
e.g. compensation value too high/too low, voltage at reservoir capacitor is too low
«Functional state 3» corresponds to «Fault»
e.g. data fault in the EEPROM, beam interruption, compensation value is invalid
Compensation value
The compensation value (NFW) is the reference variable for the actual measurement sig-
nal. All thresholds, diagnostic functions and self-checking are based on the current com-
pensation value.
The first compensation value (NFW) is set at the time of initialization. It is subsequently
updated approx. every 60 minutes to compensate a slow drift of the measurement signal.
This drift can be caused, for example, by contamination of the detector optics.
The maximum compensation is 50% of the total signal of 100%.
Response threshold
The response threshold corresponds to a danger level.
An alarm algorithm is activated when the response threshold drops.
According to the sensitivity setting, the response threshold is higher or lower.
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