Emerson Micro Motion 3711, Руководство по конфигурации и использованию, Страница: 131 / 234

Configuration and Use Manual 123
Function Sequence Tables
PID Contr
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Monitoring and Displa
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11.8.3 Comparison commands
Use comparison commands to compare values. Comparison commands conditionally compare two
values, and branch to a different sequence of commands if the comparison is determined to be
true
.
Otherwise, if the comparison is determined to be
false
, no branching occurs and the next command in
sequence is executed. Comparison commands test values for equivalence (==), non-equivalence (!=),
less than (<), less than or equal to (<=), greater than (>) , and greater than or equal to (>=).
Example The following FST checks AI alarm status using the
FST logical command AND.
The FST reads the current AI alarm status value and
checks for a high alarm (bit weight = 4), high-high
alarm (bit weight = 8), and a point failure alarm (bit
weight = 64). The FST then activates a DO if any of the
alarms is active; otherwise, the FST deactivates the
DO.
Note that the value operated on by a logical command
must be read into the compare flag before the
command is executed, and saved out afterwards.
VAL AIN E5, ALARM
SAV FST 1, CMPFLG
AND 76
VAL FST 1, CMPFLG
!= 0 ALARM
DO DOU B4, STATUS 0
GO DELAY
ALARM DO DOU B4, STATUS 1
DELAY WT 5
END
Table 11-8 Logical commands
Name Description Arguments Results
NOT Logical NOT of SVD(in) None • If SVD(in) > 0, SVD(out) = 0
• Otherwise, SVD(out) = 1
AND Logical AND ARG1 with SVD(in) • ARG1 = Database or Constant
Value
SVD(out) = [SVD(in) AND ARG1]
OR Logical OR ARG1 with SVD(in) • ARG1 = Database or Constant
Value
SVD(out) = [SVD(in) OR ARG1]
XOR Logical XOR ARG1 with SVD(in) • ARG1 = Database or Constant
Value
SVD(out) = [SVD(in) XOR ARG1]