Functions And Operation Examples - Mitsubishi Electric FX3G SERIES Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
4.4.2

Functions and operation examples

1. General type
S 2
Start
S 20
Lower
limit
S 21
Clamping
S 22
Upper
limit
State relays have many NO contacts and NC contacts in the same way as
auxiliary relays, and such contacts can be used arbitrarily in sequence
programs.
When state relays (S) are not used for step ladder instructions, they can be used
in general sequences in the same way as auxiliary relays (M) (as shown in the
figure on the right).
2. Latched (battery backed) type
• Latched (battery backed) type state relays store their ON/OFF status even if the power is shut down while the PLC
is operating, so the operation can be restarted from the last point in the process.
In FX /FX
3U 3UC
In FX PLCs, latched type devices are backed up by the EEPROM built into the PLC. When the optional battery
3G
is installed, the battery backs up some general type devices.
• When using latched (battery backed) type state relays as general
type state relays, provide a reset circuit shown in the right figure
around the head step in the program.
92
Initial state
Start
X000
Moving down
Lower limit
X001
Clamping
X002
Upper limit
X003
PLCs, latched (battery backed) type devices are backed up by the battery built into the PLC.
In the stepping type process control shown in the left
figure, when the start signal X000 turns ON, the state relay
S20 is set (turned ON) and the solenoid valve Y000 for
moving down turns on.
TRAN
When the lower limit switch X001 turns ON the state relay
S21 is set (turned ON) and the solenoid valve Y001 for
clamping turns on.
Y000
When the clamp confirmation limit switch X002 turns ON,
the state relay S22 is set (turned ON).
When the operation proceeds to the next step, the state
TRAN
relay in the preceding step is automatically reset (turned
Clamping
OFF).
Y001
When the PLC turns OFF, all of general type state relays
are turned OFF.
When the ON/OFF status just before power failure is
TRAN
required, use latched (battery backed) type state relays.
Moving up
Y002
TRAN
→ For details on backup against power failure, refer to Section 2.6.
Ex. Fx
0
4 Devices in Detail
4.4 State Relay [S]
X001
S10
/FX PLCs
3U 3UC
M8002
FNC 040
S1000
ZRST
Initial pulse
S1000 to S1200 are initialized.
S10
M30
Y005
S1200