Maintenance
Fail-Safe Operation
91
and the assigned analog output (current) value (see Table 12) will be set. For instance, in 2-
Color mode, if the internal ambient temperature is over the limit and the attenuation is to high
too, the unit outputs EIHH to the temperature display and sets an analog output current of 21
mA on the analog current loop output lines. However, since 2-Color wide band and narrow band
temperatures may all be presented simultaneously through RS485 or LAN / Ethernet interface,
their over and under range conditions are independent.
Following order shows the priorities of the possible failsafe conditions:
1. Heater control temperature over range highest priority
2. Heater control temperature under range
3. Internal temperature over range
4. Internal temperature under range
5. Wide band detector failure
6. Narrow band detector failure
7. Energy too low
8. Attenuation too high (> 95%)
9. Attenuation > 95% (“dirty window”)
10. 2-Color temperature under range
11. 2-Color temperature over range
12. Wide band temperature under range
13. Wide band temperature over range
14. Narrow band temperature under range
15. Narrow band temperature over range lowest priority
Examples of failsafe conditions:
1. 1-Color temperature is selected to show on the temperature display. 2-Color
temperature is transmitted in burst mode. Wide band temperature is under range. The
2-Color temperature is 999°C.
Outputs:
Temperature Display: EUUU
RS485 or LAN/Ethernet: C T999.0
Analog Output: 2 to 3 mA
Relay: abnormal state
2. 2-Color temperature is selected to show on the temperature display. All three
temperatures are transmitted in burst mode. Two-color temperature is 1021.0°C. Wide
band temperature is 703.0°C. Narrow band temperature is 685.0°C. Attenuation is
above 95%, the “dirty window” threshold.
Outputs:
Temperature Display: 1021.0
RS485 or LAN/Ethernet: C T1021.0 W703.0 N685.0
Analog Output: scaled to temperature, between 4 and 20 mA
Relay: abnormal state
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