Mitsubishi Electric MELSEC-Q Structured Programming Manual page 49

FXCPU Structured Programming Manual
[Device & Common]
2. Latched (backed-up) type
• Latched (backed-up) 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 after shutdown from the previous last point in the
process.
Latched (backed-up) type state relays are backed up by a battery, EEPROM, etc. built in the PLC.
• When using latched (backed-up) type state relays as
general type state relays, provide a reset circuit shown in
the right figure around the head step in the program.
3. Annunciator type
Annunciator type state relays can be also used as outputs for external fault diagnosis.
For example, when an external fault diagnosis circuit shown in the figure below is created and the contents of
the special data register D8049 are monitored, the smallest number out of the active state relays S900 to
S999 is displayed.
If two or more faults have occurred, the smallest state relay number having a fault is displayed at first. When
the displayed fault is cleared, the next smallest state relay number having a fault is stored in D8049 and
displayed.
M8000
RUN monitor
Y000 X000
X001 X002
X003 X004
K100
M8048
X005
While the special auxiliary relay M8049 is not driven, annunciator type state relays can be used as latched
(backed-up) type state relays in sequence programs in the same way as general type state relays.
M8049
ANS
EN ENO
s d
T0 S900
m
K10
ANS
EN ENO
s d
T1 S901
m
K20
ANS
EN ENO
s d
T2 S902
m
Y010
ANRP
EN ENO
→ For details on each backup method, refer to Section 1.2.
M8002
Initial pulse
·
When the special auxiliary relay M8049 is driven, monitoring
becomes valid.
·
If the forward end detection input X000 is not activated within
1 second after the forward output Y000 is driven, S900 is
activated.
·
If both the upper limit detection input X001 and the lower limit
detection input X002 are deactivated at the same time for 2
seconds or more, S901 is activated.
·
In a machine whose takt time is less than 10 seconds,if the
switch X004 which is designed to be activated during one-cycle
operation of the machine is not activated while the continuous
operation mode input X003 is ON, S902 is activated.
·
When any of annunciator type state relays S900 to S999 turns
ON, the special auxiliary relay M8048 is activated and the fault
display output Y010 is activated.
·
The state relays activated by the external fault diagnosis program
can be turned OFF by the reset button X005.
Every time X005 is set to ON, the active annunciator type state
relay having the smallest number is reset in turn.
2 Devices in Detail
2.4 State Relay [S]
ZRST
EN ENO
d1
S1000
d2
S1200
S1000 to S1200
are initialized.
47
1
2
3
4
5
6
7