Rockwell-automation T8019 Trusted Process Control Algorithm Software P Manuale Utente Scaricare il pdf (Pagina 10)

Trusted

Process Control Algorithms T8019

Issue 8 Sep 07 PD-T8019 10

1.3. Analogue Select

R_SEL

PV1

OUT

PV2

SEL

The process variables (PV1 and PV2) and the output (OUT) must all be of type REAL

. The select

signal (SEL) is of type BOOLEAN. When SEL is FALSE, PV1 is copied to the output; when SEL is

TRUE, PV2 is copied to the output.

if SEL

Set OUT = PV2

else

Set OUT = PV1

end if

Out is finite if, and only if, the selected PV1 or PV2 is finite.

1.4. Multiple Value Averaging

AVG

OUT

PV1

PV2

PV3

PV4

PV5

PV6

PV7

PV8

PV9

PV10

The multiple value averaging calculates the average of between 1 and 10 values (PV1 to PV10). N

specifies the number of values averaged; the first N values are averaged. E.g. if N=3, the average of

PV1, PV2 and PV3 is returned. N is of type INTEGER, PV1 to PV10 and OUT are of type REAL. All

input values must be connected; unused inputs should be tied to either one of the other used inputs or

a constant value.

If the value of N is out of range, i.e. 1>N>10, the average of all ten input values is to be returned and

the “param” error count incremented. Overflow errors occurring whilst calculating the average are to

result in a value of PV1 being returned and the “overflow” error count incremented. If an “underflow”

condition occurs, the function is to set OUT to zero and increment the “underflow” error counter.

The standard ISaGRAF SEL function provides the equivalent operation for integer values.

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Rockwell-automation T8019 Trusted Process Control Algorithm Software P Manuale Utente Pagina 10