Mitsubishi Electric MELSEC FX3U Programming Manual page 807

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
3. Assigning devices
Assign devices of a PLC in the created process drawing.
1) Assign a state relay
process.
At this time, assign a state relay (S0 to S9) to the initial
process.
After the first process, arbitrarily assign state relay numbers
(S20 to S899) except the initial state relays.
(There is no relationship between state relay numbers and
order of processes.)
There are latched (battery backed) type state relays whose
ON/OFF status is stored against power failure.
The state relays S10 to S19 are used for special purposes
when the IST (FNC 60) instruction is used.
2) Assign a device (input terminal number connected to a
pushbutton switch or limit switch, timer number, etc.) to
each transfer condition.
NO contact and NC contact are available for a transfer
condition.
If there are two or more transfer conditions, AND circuit or
OR circuit is available.
3) Assign a device (output terminal number connected to
external equipment, timer number, etc.) used for an
operation performed in each process.
Many devices such as timers, counters and auxiliary relays
are provided in a PLC, and can be used arbitrarily.
The timer T0 is used here. Because T0 works by the 0.1
sec clock, the output contact turns ON five seconds after a
coil is driven when the set value is K50.
If there are two or more loads such as timers and counters
which are driven at the same time, two or more circuits can
be assigned to one state relay.
4) When performing repeated operations or skipping some
processes (jump operation), use "
destination state relay number.
In this example, only the SFC program creating procedure is explained. In practical cases, a circuit for setting
the initial state relay to ON is required to execute the SFC program.
Create a circuit for setting the initial state relay to ON using the relay ladder.
At this time, use SET instruction to set the initial state relay to ON.
Initial pulse
M8002
to a rectangle indicating a
S
" and specify the jump
SET S0
35 SFC Program and Step Ladder
35.1 SFC Program
S0
Start switch
X000
Y023
S20
Limit switch for minor
X001
forward movement
Y021
S21
Limit switch for
X002
backward movement
S22
Timer
T0
Y023
S23
Limit switch for major
X003
forward movement
Y021
S24
Limit switch for
X002
backward movement
S0
31
32
Y021
Forward
33
Y023
Backward
34
T0
K50
Stop timer
Y021
Forward
35
Y023
Backward
36
37
38
A
B
805