Technical reference
A.10 Failsafe
SITRANS Probe LR with mA/HART
Operating Instructions, 05/2019, A5E32337711-AC
91
A.10
Failsafe
The Failsafe function can be activated either if there is not a valid measurement, or by one of
the faults marked by an asterisk in the table General Fault Codes on page 84. In Failsafe
mode, the device will output one of the four options determined by P071 (Failsafe Material
Level).
Failsafe mode P071
1= HI
Use Maximum mA limit (P213) as material level
2= LO
Use Minimum mA limit (P212) as material level
3= HOLd
Level remains at last reading
4=SEL
User selected value (defined in P073)
If an invalid measurement is generated by the application (for example, material level outside
threshold settings), the Failsafe timer (P070) will control the speed of the Failsafe response.
When the Failsafe timer expires, the device outputs the value selected in P071. If a valid
measurement is received before the timer expires, the timer will be reset.
If failsafe mode is activated by a fault (see General fault codes (Page 74)), the instrument
will go into failsafe mode without delay.
A.11
Chemical compatibility
The plastic materials used in the construction of SITRANS Probe LR (polypropylene,
polybutylene terephthalate (PBT), and Polyether Imide (PEI)), are resistant to attack from
most chemicals. For exposure to specific environments, check with chemical compatibility
charts before installing and operating SITRANS Probe LR in your application.