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FX Series Programmable Controlers Applied Instructions 5
5-90
5.8.9 FROM (FNC 78)
Operation:
The FROM instruction reads n words of data
startin
g
from the buffer memor
y
address m
2
of the
special function block with the lo
g
ical block
position specified as m
1,
The read data is stored in the PLC at head address D for n word
devices.
Points to note:
a) All special function blocks which are addressable with the FROM/TO instructions are
connected to the extension bus on the ri
g
ht hand side of the PLC. Each special function
block can be inserted at an
y
point within the chain of extended units (as lon
g
as the s
y
stem
confi
g
uration rules are not broken). Each special function block is consecutivel
y
addressed
from 0 to 7 be
g
innin
g
with the one closest to the base unit.
b) Each special function unit has different buffer memor
y
re
g
isters. These often have a
dedicated use for each individual unit. Before an
y
readin
g
or writin
g
of data is undertaken
ensure that the correct buffer memor
y
allocations for the unit used are known.
m
2
: This defines the head address of the (special function blocks) buffer memories bein
g
accessed. m
2
ma
y
have a value from the ran
g
e 0 to 31.
n: This identifies the number of words which are to be transferred between the special
function block and the PLC base unit. n ma
y
have a value of 1 to 31 for 16 bit operation but
a ran
g
e of 1 to 16 is available for 32 bit operation.
c) The destination head address for the data read FROM the special function block is
specified under the D operand; and will occup
y
n further devices.
d) This instruction will onl
y
operate when the drive input is ener
g
ized.
Mnemonic Function
Operands
Program steps
m
1
m
2
Dn
FROM
FNC 78
(FROM)
Read data from
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
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
FROM,
FROMP:
9 steps
DFROM,
DFROMP:
17 steps
FROM K2 D10K10 K6
[ m1 ][ m2 ] [ D ] [ n ]
X1
POWER
FX-8EYT
POWER
FX-4AD
POWER
FX-1HC
POWER
FX-2DA
24V
A-D
OFFSET
GAIN
READY
CH1
CH2
CH3
CH4
24V
D-A
OFFSET
GAIN
UP
DOWN
CH1
READY
CH2
Special function
block 0
Output block
Y50-57
Special function
block 1
Special function
block 2
FX-80MR