408
Number of words
to be read
PC Memory
Beginning address
to be read
Words allocated to
Special I/O Unit
(CIO Area)
D: First destination word
S: Source word
Special I/O Unit Memory
5-35-3 I/O WRITE: WRIT(191)
Variations
j WRIT(191)
(191)
WRIT N S D
S: 1
st
source word CIO, G, A, T, C, DM
D: Destination word CIO
N: Words to transfer CIO, G, A, T, C, #, DM, DR, IR
Operand Data AreasLadder Symbol
When the execution condition is OFF, WRIT(191) is not executed. When the
execution condition is ON, WRIT(191) transfers the contents of S through
S+(N–1) to the Special I/O Unit allocated word D. N indicates the number of
words to be read. D indicates the rightmost (first) of the two words allocated for
the Special I/O Unit (i.e., the output word).
N must be BCD. (Special I/O Units can transfer up to 255 words of data.)
D must be in the I/O Area and allocated to a Special I/O Unit.
If a Special I/O Unit is busy and unable to receive data, the data will be written
during the next cycle. To make sure that WRIT(191) execution has been com-
pleted, check EQ (A50006).
A maximum of two READ(190)/WRIT(191) instructions can be used for Slaves
connected to the same Master. If a third instruction is attempted when two
instructions are already being executed, the third instruction will not be executed
Description
Precautions
Special I/O Instructions Section 5-35
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