KROHNE TT 51 SERIES EN - Manual (Page 9)

SAFETY FUNCTION
4
9
TT 51 SERIES
www.krohne.com 09/2010 - 4000869801 - AD TT 51 SIL R01 en
4.3.2 Sensor backup
If "Sensor backup" function is activated the sensor chosen as output measuring in the
configuration will reflect the actual measuring value as long as it’s working properly. A sensor
break or a sensor short cause the transmitter to switch over to the other sensor and the output
signal will reflect the measured value of that sensor. A diagnostic message is transmitted via
HART
® to the PLC.
If the "Average" function is activated in the configuration, the output value will reflect the actual
mean measuring value as long as the sensors are working properly. A sensor break or a sensor
short cause the transmitter to switch over to the non-broken sensor and the output signal will
reflect the measured value of that sensor. A diagnostic message is transmitted via HART
® to the
PLC.
INFORMATION!
The functions "Sensor backup" and "Average" doesn't give any extra safety according to SIL and
are not used for calculating the system (transmitter + sensor) safety figures.
CAUTION!
The possibility to select the function for sensor drift monitoring is implemented in software
revision IPM-SW 01.01.03 and OPM-SW 01.01.04, from serial number 1006.xxxxxx.
.book Page 9 Thursday, September 9, 2010 4:19 PM