System alarms

Full format options report system error alarms (System alarms and descriptions). Most errors are checked every 10 seconds, then the message output is updated. The following errors are checked at a different rate:

  • Signature error—checked and reset at power up.

  • Flash read and write errors—checked when flash memory is updated (for example, when changes are made through the memory structure). These errors are also reset on power up.

  • Particle limit—checked every minute and reset when read.

System alarms and descriptions

Alarm

Range

Description

Emitter failure (emitter hoods main LED output power level)

0 to 2
  1. Everything is within normal parameters
  2. Light output level too low
  3. Light output level too high

Emitter lens dirty1

0 to 3

  1. OK; the reported attenuation is below 10%
  2. Reported window signal value out of range (>30%); possible sensor fault or blocked hood
  3. Slight dirt build up (10% signal attenuation or higher)
  4. High level of dirt build up (>20%)

Emitter temperature

0 to 3

  1. Temperature within operating conditions
  2. Too low, less than –40 °C
  3. Too high, over 80 °C
  4. No sensor detected or below –54 °C

Detector lens dirty1

0 to 3

  1. OK; the reported attenuation is below 10%
  2. Reported window signal value out of range (>30%); possible sensor fault or blocked hood
  3. Slight dirt build up (10% signal attenuation or higher)
  4. High level of dirt build up (>20%)

Detector temperature

0 to 3

  1. Temperature within operating conditions
  2. Too low, less than –40 °C
  3. Too high, over 80 °C
  4. No sensor detected or below –54 °C

Detector DC saturation level (amount of background light seen by the detector hood)1

0 or 1
  1. Within limits
  2. Saturated; the sensor may not be able to perform visibility readings in some circumstances, possibly due to high level of reflections into the detector.

Hood temperature

0 to 3

  1. Temperature within operating conditions
  2. Too low, less than –40 °C
  3. Too high, over 80 °C
  4. No sensor detected or below –54 °C

External temperature

0 to 3

  1. Temperature within operating conditions
  2. Too low, less than –40 °C
  3. Too high, over 80 °C
  4. No sensor detected or below –54 °C

Signature error

0 to 4
  1. No fault
  2. OS signature error at power up
  3. User memory signature did not match when last reading
  4. User memory fault at power up; secondary copy was reinstated to correct error.
  5. User memory fault at power up; no secondary copy was found to reinstate. Factory defaults have been reinstated. System will need re-calibrating.

Flash read error

0 or 1
  1. No errors
  2. One or more errors reading user variables from flash occurred

Flash write error

0 or 1
  1. No errors
  2. One or more errors writing user variables to flash occurred

Particle limit

0 or 1
  1. No errors
  2. More particles detected than can be processed

1With operating system 14 onwards, to avoid short term appearance of alarms caused by transient events (such as insects or raindrops on the lens) the condition that triggers an increase in alarm level must persist for 15 minutes before the alarm is set.