<4. Explanation of Basic Item>
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IM 12A01A02-72E
3rd Edition : Oct. 01, 2015-00
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Fail Safe Mode (FSAFE_TYPE)
Fail Safe Mode is parameter used to define the reaction of the device, if a BAD status of signal
to AI function block (OUT.Status and OUT.Value) is detected. This is available only when Target
Mode of AI function block is in “Auto”.
Fail Safe Mode defines the Output Value and Status (Quality) when status of input signal to AI
function block is BAD.
This function is valid only when Actual Mode of AI function block is in “AUTO”
Table 4.3 Fail Safe Mode (Classic Status)
Fail Safe Mode
Output Value and Status (Quality)
Default value is used as
output value
Value Fail Safe Default value
Status UNCERTAIN - Substitute Value
Storing last valid output
value
Value Last stored valid OUT value
Status UNCERTAIN - Last Usable Value
The calculated output value
is incorrect
Value Wrong calculated value
Status BAD - *(* as calculated)
Table 4.4 Fail Safe Mode (Condensed Status)
Fail Safe Mode
Output Value and Status (Quality)
Default value is used as
output value
Value Fail Safe Default value
Status BAD - Passivated, Constant *1
UNCERTAIN - Substitute Set *2
UNCERTAIN - Process Related *3
UNCERTAIN - Substitute Set *4
Storing last valid output
value
Value Last stored valid OUT value
Status BAD - Passivated, Constant *1
UNCERTAIN - Substitute Set *2
UNCERTAIN - Process Related *3
UNCERTAIN - Substitute Set *4
The calculated output value
is incorrect
Value Wrong calculated value
Status BAD - Passivated, Constant *1
BAD - Maintenance Alarm *2
BAD - Process Related *3
BAD -Function Check *4
*1:
When input status = BAD - Passivated
*2:
When input status = BAD - Maintenance Alarm
*3:
When input status = BAD - Process Related
*4:
When input status = BAD - Function Check