Vlim Function Block - Honeywell UMC800 Reference Manual

2.77 VLIM Function Block

Description
The VLIM label stands for Velocity (Rate) Limiter. This block is part of the Auxiliary category. It looks
like this graphically on the Control Builder.
Function
Limits the rate at which an analog input value (X) can change, when a digital input signal (EN) is ON.
Individual rate of change limits are configured for an increasing and a decreasing X, respectively.
Separate digital status outputs indicate when High(H) or Low(L) rate limits are active.
• If EN = OFF or system state = NEWSTART*, then:
OUT = X,
L
H
• If EN = ON and OUT < X, then:
OUT moves toward X at Increasing RATE limit,
L
H
• If EN = ON and OUT > X, then:
OUT moves toward X at Decreasing RATE,
L
H
* Newstart is the first scan cycle following the cold start of the controller.
Input
X = Analog Value (Primary Input)
EN = Enable Input command
Output
OUT = Rate Limited Input Value
H = High Rate alarm indication
L = Low Rate alarm indication
3/99
= OFF,
= OFF.
= OFF,
= ON until OUT = X.
= ON until OUT = X,
= OFF.
Function Block Reference Guide
Function Blocks
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