4
General Instruction Characteristics Section 1-1
• An upwardly differentiated instruction is executed only once after its exe-
cution condition goes from OFF to ON.
• A downwardly differentiated instruction is executed only once after its exe-
cution condition goes from ON to OFF.
Note The downwardly differentiated option (%) is available only for the LD, AND,
OR, and RSET instructions. To create downwardly differentiated variations of
other instructions, control the execution of the instruction with work bits con-
trolled with DIFD(014) or DOWN(522).
1-1-3 Instruction Variations
The variation prefixes (@, %, and !) can be added to an instruction to create a
differentiated instruction or provide immediate refreshing.
Variation Instruction type Operation Format Example
Non-
differentiated
Output instructions
(instructions requiring
an execution condi-
tion)
The instruction is exe-
cuted every cycle while
the execution condition is
true (ON).
Input instructions
(instructions used as
execution conditions)
The bit processing (such
as read, comparison, or
test) is performed every
cycle. The execution con-
dition is true while the
result is ON.
Upwardly
differentiated
(with @ prefix)
Output instructions The instruction is exe-
cuted just once when the
execution condition goes
from OFF to ON.
Input instructions
(instructions used as
execution conditions)
The bit processing (such
as read, comparison, or
test) is performed every
cycle. The execution con-
dition is true for one cycle
when the result goes
from OFF to ON.
Downwardly
differentiated
(with % prefix)
Output instructions The instruction is exe-
cuted just once when the
execution condition goes
from ON to OFF.
Input instructions
(instructions used as
execution conditions)
The bit processing (such
as read, comparison, or
test) is performed every
cycle. The execution con-
dition is true for one cycle
when the result goes
from ON to OFF.
Output instruction
executed each cycle
MOV
Input instruction
executed each cycle
Instruction executed
once for upward
differentiation
@MOV
MOV(021) executed once
for each OFF to ON transi-
tion in CIO 000102.
Upwardly differentiated
input instruction
ON execution condition created
for one cycle only for each OFF
to ON transition in CIO 000103.
%Instruction
executed once for
downward
differentiation
0001
02 %SET
SET executed once for
each ON to OFF transition
in CIO 000102.
Downwardly differentiated
input instruction
0001
03
ON execution condition created
for one cycle only for each ON to
OFF transition in CIO 000103.
Variation Prefix Operation
Differentiation Upwardly dif-
ferentiated
@ Creates an upwardly differentiated instruc-
tion.
Downwardly
differentiated
% Creates a downwardly differentiated instruc-
tion.
Immediate refreshing ! The instruction’s operand data in the I/O
Area will be refreshed when the instruction
is executed.
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