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Function Blocks
STG Stage Function Block
364
HC900 Hybrid Control Designer Function Block Reference Guide
Revision 11
2/07
STG Stage Function Block
Description
The
STG
label stands for
Stage
.
This block is part of the
Auxiliary
category.
Function
The Stage (STG) function block provides differential On/Off control and is typically used to monitor
pressure and flow for controlling pumps and operating valves.
There are four individual stages grouped together in the function block. The block monitors from one to
two analog inputs (PV1, PV2) which are common to all four stages, compares them for each stage by a
configurable comparator, and provides On/Off control outputs for the four stages based on configurable
setpoints for each stage. Each stage can be individually enabled and forced ON or OFF (OVON/OVOFF)
Interlocking
Previous
interlocking prevents a stage’s output from turning ON until the previous stage has
turned ON.
Next
interlocking prevents a stage’s output from turning OFF until the output of the next
stage in sequence has turned OFF.
Interlocking is provided for stages where the output of the stage is dependent on the state of the
previous and next stage. It also works across sequentially connected function blocks.
In order for interlocking between function blocks to operate, the interlocking Input/Output pin of a
STAGE function block must be directly connected (or with a signal tag) to another STAGE function
block interlocking Input/Output pin. An improper connection, such as inserting another function block
type between two successive Stage blocks, invalidates the interlock signal.
Each configuration is limited to 8 stage function blocks.
The general forcing of outputs is not permitted within this block.