FX Series Programmable Controlers Applied Instructions 5
5-67
5.7.1 IST (FNC 60)
Operation:
This instruction automaticall
sets up a multi-mode
STL operatin
s
stem. This consists of variations
of ‘manual’ and ‘automatic’ operation modes.
Points to note:
a) The IST instruction automaticall
assi
ns
and uses man
bit fla
s and word devices;
these are listed in the boxed column on the
ri
ht of this pa
e.
b) The IST instruction ma
onl
be used
ONCE
.
It should be pro
rammed close to the
be
innin
of the pro
ram, before the
controlled STL circuits.
c) The required operation mode is selected b
drivin
the devices associated with
operands
S+0throu
h to S+4(5 inputs). None of the
devices within this ran
e should be ON at
the same time. It is recommended that these
‘inputs’ are selected throu
h use of a rotar
switch.
If the currentl
selected operatin
mode is
chan
ed before the ‘zero return complete’
fla
(M8043) is set, all outputs will be turned
OFF.
d) The ‘zero position’ is a term used to identif
a datum position from where the controlled
device, starts from and returns too after it
has completed its task. Hence, the operatin
mode ‘zero return’, causes the controlled
s
stem to return to this datum.
Mnemonic Function
Operands
Program steps
S
1
S
2
S
3
IST
FNC 60
(
Initial
state)
Automaticall
sets
up a multi-mode
STL operatin
s
stem
X, Y, M, S,
Note:
uses 8
consecutive devices
S,
Note:
FX
0
users S20 to S63
FX0N users S20 to S127
FX users S20 to S899
D1must be lower than D2
IST:
7 steps
M8000
S20X20 S40IST
[ S ] [ D1 ] [ D2 ]
Indirect user selected devices:
Automatic operation start
S0 initiates ‘manual’ operation
S1 initiates ‘zero return’ operation
S2 initiates ‘automatic’ operation
S10 to S19 ‘zero return’ sequence
‘automatic return’ sequence
M8040 = ON STL state transfer is inhibited
M8041 = ON initial states are enabled
M8042 = Start pulse given by start input
M8043 = ON zero return completed
M8044 = ON machine zero detected
M8047 = ON STL monitor enabled
The ‘zero’ position is sometimes also referred to as a home position, safe position, neutral
position or a datum position.
