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
from the buffer memor
address m
2
of the
special function block with the lo
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
ht hand side of the PLC. Each special function
block can be inserted at an
point within the chain of extended units (as lon
as the s
stem
confi
uration rules are not broken). Each special function block is consecutivel
addressed
from 0 to 7 be
innin
with the one closest to the base unit.
b) Each special function unit has different buffer memor
re
isters. These often have a
dedicated use for each individual unit. Before an
readin
or writin
of data is undertaken
ensure that the correct buffer memor
allocations for the unit used are known.
m
2
: This defines the head address of the (special function blocks) buffer memories bein
accessed. m
2
ma
have a value from the ran
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
have a value of 1 to 31 for 16 bit operation but
a ran
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
n further devices.
d) This instruction will onl
operate when the drive input is ener
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
