Page 228 - Programmable Logic Controllers, Fifth Edition - Mobile version

N7:20 00 00 1 1 1 1 0 00 0 1 1 1 1 • The instruction may be programmed with input
Original data stored in registers N7:30 and N7:20 conditions preceding it, or it may be programmed
unconditionally.
N7:28 A Masked Move (MVM) instruction functions like a
N7:29
N7:30 1 1 00 1 1 1 00 1 1 0 1 1 1 0 standard move (MOV) instruction, except that a masked
N7:31 move allows data to be filtered out that is not required to
(a) be moved. The mask parameter specified in the instruc-
tion block is what performs this filtering process. This
N7:20 1 1 00 1 1 1 00 1 1 0 1 1 1 0 mask parameter can be either a word address location or a
Data transferred from register N7:30 to N7:20
numerical constant. The operation of the mask parameter
can be summarized as follows:
N7:28
N7:29 • The pattern of characters in the mask determines
N7:30 1 1 00 1 1 1 00 1 1 0 1 1 1 0 which source bits will be passed through to the des-
N7:31 tination address.
(b)
• The bits in the mask that are set to zero (0) do not
Figure 10-3 Data transfer concept. pass data.
• Only the bits in the mask that are set to one (1) will
Data transfer instructions can address almost any loca- pass the source data through to the destination.
tion in the memory. Prestored values can be automatically • Bits in the destination are not affected when the cor-
retrieved and placed in any new location. That location responding bits in the mask are zero.
may be the preset register for a timer or counter or even • The MVM instruction is used to copy the desired part
an output register that controls a seven-segment display. of a 16-bit word by masking the rest of the value.
SLC 500 controllers use a block-formatted move
(MOV) instruction to accomplish data moves. The MOV Figure 10-5 shows an example of a mask move (MVM)
instruction is used to copy the value in one register or word instruction. This instruction transfers data through the
to another. This instruction copies data from a source reg- mask from the source address, B3:0, to the destination
ister to a destination register. Figure 10-4 shows an exam- address, B3:4. The operation of the program can be sum-
ple of the MOV instruction. The operation of the program marized as follows:
can be summarized as follows: • The mask may be entered as an address or in hexa-

• When the rung is true, input switch A closed, the decimal format, and its value will be displayed in
value stored at the source address, N7:30, is copied hexadecimal.
into the destination address, N7:20.
• When the rung goes false, input switch A opened, Ladder logic program
the destination address will retain the value unless it Input
is changed elsewhere in the program. L1 A MVM
A MASKED MOVE
• The source value remains unchanged and no data Source B3:0
conversion occurs. 1010101010101010 B3:1
Mask
FF0F
N7: Integer table Destination B3:4
Input Ladder logic program 1010101011001010

L1 N7:20
A 10101010 1010 1010 Source B3:0
A MOV
MOVE 11111111 0000 1111
Source N7:30 Mask FF0F
Destination N7:20 11001100 1100 1100 Destination B3:4 before instruction
went true
10101010 1100 1010 Destination B3:4 after instruction
N7:30 went true

Unchanged
Figure 10-4 SLC 500 block-formatted move instruction. Figure 10-5 Masked move (MVM) instruction.

Data Manipulation Instructions Chapter 10 209

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