ISEL Function Block
March 2006
5-103
START
Bad
At least 1 good
input?
SELECT_TYPE
Middle or
Average?
Selected in-
put status?
Propagate Good
Noncascade
Bad
Good
Good
Yes
No
One input?
Yes
No
No
Multiple
Inputs
MODE_BLK
MAN?
STATUS_OPTS
Uncertain if Man
Mode?
Propagate Good
Noncascade
Yes
Yes
No
No
1
1
NOTES:
1
Yes
Yes
Figure 5-16. Input Selector Block Substatus Propagation
Propagate Bad,
Out of Service
MODE_BLK
O/S?
Yes
No
Propagate
Uncertain
MODE_BLK
must be Auto
OP_SELECT
status?
Propagate Bad,
Nonspecific
OP_SELECT
value >0?
Propagate Bad,
Nonspecific
Yes
No
Propagate
Nonspecific
Propagate input
substatus as is
SELECT_TYPE
Maximum or
Minimum?
One input?
Yes
All inputs with
same value?
Propagate input
substatus as is
Yes
No
Propagate
Nonspecific
AN INPUT STATUS MAY BE BAD, GOOD, OR UNCERTAIN. IF BAD, THE INPUT IS NOT USED AND THE STATUS IS PROPAGATED AS BAD WITH
SUBSTATUS NON-SPECIFIC. IF GOOD IT IS USED AND THE STATUS IS PROPAGATED AS GOOD (NON-CASCADE). IF UNCERTAIN, AND STATUS_OPTS
IS “USE UNCERTAIN AS GOOD” THEN THE INPUT IS USED AND THE STATUS IS PROPAGATED AS GOOD (NON-CASCADE), OTHERWISE IT IS NOT
USED AND THE STATUS IS PROPAGATED AS BAD WITH SUBSTATUS NON-SPECIFIC.
Multiple
Inputs
Yes
No
SELECT_TYPE
Must be First
Good or Hot
Spare?
Illegal Select Type
should never be reached
5