Allen-Bradley ProcessLogix 1756-IA16, Справочное руководство, Страница: 105 / 120

Publication 1757-RM810A-EN-P - May 2002
Functional Blocks 3-65
The major use of the PUSH FB is to push the value of different data
types to the output destination. The function block fetches the input
when it is scheduled to run and stores the output in the same
execution cycle after the type conversion. If data type conversion is
not necessary, then none will be done.
The figure below shows a diagram of the PUSH function block. The
different input and output pins shown in the diagram are the default
exposed pins, but these are not the only available data types for
conversion. Only the most frequently used data types for conversion
are shown as the default pins on the block.
Figure 1 PUSH Function Block
Other PUSH block functions include:
•
The store-to-input pin is not accepted. If the PUSH block is able
to fetch the value, then it is pushed to the destination.
•
There are two statuses provided; EXECSTS and STORESTS.
These will give the user indication of the status of fetching input
and status of output store (refer to page 3-67 for more details).
•
Whether the value is stored to destination or not can be
controlled by STOREENB. If this is OFF, only the first time store
on CM or CEE change occurs. No other store happens unless the
STOREENB is set to ON.
•
There is also capability to only store values on change. If
STORONCHGENB is set to ON, the input values are stored to
the destination ONLY when the input is changed. In the case of
a floating point number, the value is considered changed only if
the absolute value of the difference between the new value and
the last value is larger than the configured INPUTCHGDB.
•
BOOLVALUEOFF, BOOLVALUEON and
ENUMTOBOOLMAP[0..63] behave the same as in the
TypeConvert block (see page 3-69).
PUSH
IN.BOOLEAN
IN.INT32
IN.FLOAT64
IN.ENUM
OUT.BOOLEAN
OUT.INT32
OUT.FLOAT64
OUT.ENUM
EXECSTS
42777
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