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FX Series Programmable Controlers Applied Instructions 5
5-91
e) Users of FX PLC’s have the option of allowin
g
interrupts to occur immediatel
y
, i.e. durin
g
the
operation of the FROM/TO instructions or to wait until the completion of the current FROM/TO
instruction. This is achieved b
y
controllin
g
the special auxiliar
y
fla
g
M8028. The followin
g
table
identifies certain points associated with this control and operation.
Users of FX
0N
have no option for interruption of the FROM/TO instructions and hence
alwa
y
s operate in a mode equivalent to havin
g
M8028 switched OFF.
5.8.10 TO (FNC 77)
Operation:
The TO instruction writes n words of data to the
head buffer memor
y
address m
2
of the special
function block with the lo
g
ical block position
specified in m
1
. The written data is taken from the
PLC’s head address S for n word devices.
Points to note:
All points are the same as the FROM instruction (see previous pa
g
e) except point c) which is
replaced b
y
the followin
g
:
a) The source head address for the data written TO the special function block is specified
under the S operand.
Interruption Disabled Interruption Enabled
M8028 = OFF
M8028 = ON
Jumps called b
y
interrupt operation are dela
y
ed
until the completion of the data transfer of the
FROM/TO instruction
Jumps called b
y
interrupt operation occur
immediatel
y
A small delay of (800m +200)
µ
sec can be
expected in the worst case. Note: m = the number
of 32 bit words
Data transfer will resume upon return from the
interrupt pro
g
ram. This ma
y
not be desirable if a
FROM/TO instruction has been pro
g
rammed
within the called interrupt
Ensures that FROM/TO instructions included in
an interrupt pro
g
ram will not interact with others
elsewhere
M8028 should onl
y
be used when a ver
y
short
dela
y
is required in applications where timin
g
and
accurac
y
’s are important
Mnemonic Function
Operands
Program steps
m
1
m
2
Sn
TO
FNC 79
(TO)
Writes data to the
buffer memories
of attached
special function
blocks
K, H
Note:
m
1
= 0 to 7
K, H
Note:
m
2
=FX
(2C)
0 to 31,
FX
2N
0 to
32767
K,H, KnX,
KnY, KnM,
KnS, T, C,
D, V, Z
K, H
Note:
16 bit op:
n= 1 to 32
32 bit op:
n= 1 to 16
TO, TOP:
9 steps
DTO, DTOP:
17 steps
TO H2 D20K10 K1
[ m1 ]
[ m2 ]
[ S ]
[ n ]
X0