Chapter 16 PLC Function ApplicationsMS300
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5. ORB command: a configuration in which one block is in parallel with one device or block.
Figure 16-34
NOTE: In the case of ANB and ORB operations that connect a number of blocks, they should
be combined to form a block or network from the top down or from left to right.
6. MPS, MRD, MPP commands: branching point memory for multiple outputs that enable multiple
different outputs. The MPS command begins at a branching point, which refers to the
intersection of horizontal and vertical lines. Control relies on the contact status along a single
vertical line to determine whether the next contact can give a memory command. While each
contact is basically able to give memory commands, in view of convenience and the PLC's
capacity restrictions, this can be omitted from some places when editing a ladder diagram. You
can use the structure of the ladder diagram to judge what kinds of contact memory commands
are used.
MPS is indicated by use of the ┬ symbol. You can use this command consecutively up to
eight times.
The MRD command is read from branching point memory; because logic states along any
one vertical line must be the same, in order to continue analysis of other parts of the
ladder diagram, the original contact status must be read. MRD is indicated by the ├
symbol.
The MPP command is read from the starting state of the uppermost branching point, and it
is read from the stack (pop operation); because it is the final command along a vertical
line, it indicates that the state of the vertical line can be concluded. MPP is indicated by the
└ symbol.
Although there should basically be no errors when using the foregoing analytical approach,
the compiling program may sometimes omit identical state output, as shown in the
following diagram.
Figure 16-35
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