Loe Timer; Fail-Safe Mode; Fail-Safe Value - Siemens Sitrans LR250 Instruction Manual

LOE Timer

LOE Timer (2.4.1.) determines the length of time a Loss of Echo (LOE) condition will persist
before a Fail-safe state is activated. The default settings are dependent on the setting for
Response Rate (2.2.6.1.).
Response Rate (2.2.6.1.)
* Slow 0.1 m/min (0.32 ft/min)
Medium 1.0 m/min (3.28 ft/min)
Fast 10.0 m/min (32.8 ft/min)
Fail-safe Mode determines the level to be reported when the Fail-safe timer expires.

Fail-safe Mode

The purpose of the Fail-safe setting is to put the process into a safe mode of operation in
the event of a fault or failure. The value to be reported in the event of a fault is selected so
that a loss of power or loss of signal triggers the same response as an unsafe level.
Fail-safe mode may be triggered by a loss of echo, a bad configuration, or certain device
faults. You can select one of three possible values to be reported when a Fail-safe mode
is activated.
Fail-safe Mode FB2 (2.4.4.) determines the material level to be reported when LOE Timer
(2.4.1.) expires.
Fail-safe Mode FB1 (2.4.2.)
SUB VALUE
LAST VALUE
USE BAD VALUE

Fail-safe Value

Fail-safe Value FB1 (2.4.3.) defines the material level to be reported if the option Use
substitute value is selected in Fail-safe Mode FB2 (2.4.4.).
The two Analog Input Function blocks are set separately. For example, to set a user-
defined value for AIFB1:
• Set Fail-safe Mode FB1 (2.4.2.) to Use substitute value.
• Go to Fail-safe Value FB1 (2.4.3.) and enter the desired value.
Page 118 SITRANS LR250 (PROFIBUS PA) – INSTRUCTION MANUAL
LOE Timer
(2.4.1.)
100 min
10 min
1 min
Substitute value (Default value used as output value).
* Last value (Store last valid output value).
Use bad value (Calculated output value is incorrect).
Fill Rate (2.2.6.2.)/
Empty rate (2.2.6.3.)
0.1 m/min (0.32 ft/min)
1.0 m/min (3.28 ft/min)
10.0 m/min (32.8 ft/min)
7ML19985JF02
Filter
Time
Constant
(2.3.1.4.)
10 s
10 s
0 s