ABB REO 517 Applications Manual page 55

Logic function blocks
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The MOVE function blocks, so called copy-blocks, are used for synchronization of
boolean signals sent between logics with slow execution time and logics with fast exe-
cution time.
There are two types of MOVE function blocks - MOF located First in the slow logic
and MOL located Last in the slow logic. The MOF function blocks are used for signals
coming into the slow logic and the MOL function blocks are used for signals going out
from the slow logic.
The REx 5xx terminal contains 3 MOF function blocks of 16 signals each, and 3 MOL
function blocks of 16 signals each. This means that a maximum of 48 signals into and
48 signals out from the slow logic can be synchronized. The MOF and MOL function
blocks are only a temporary storage for the signals and do not change any value between
input and output.
Each block of 16 signals is protected from being interrupted by other logic application
tasks. This guarantees the consistency of the signals to each other within each MOVE
function block.
Synchronization of signals with MOF should be used when a signal which is produced
outside the slow logic is used in several places in the logic and there might be a mal-
function if the signal changes its value between these places.
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