LS Industrial Systems XBC-DR10E - Page 115

Chapter 5 Programming Concepts
XBC E-Type Main Unit 5-21 Ver. 1
4. Monostable timer
In general, its operation is same as off-delay timer. However, the change of input condition is
ignored while the timer is operating (decreasing). When current value reaches preset value the
timer output relay is turned off and current value is cleared.
5. Retriggerable timer
The operation of retriggerable timer is same as that of monostable timer. Only difference is that
the retriggerable timer monitors the input condition of TRTG instruction while the timer is
operating (decreasing). The current value of retriggerable timer will be set as preset value
whenever the input condition of TRTG instruction is turned on.
Remark
The Maximum timer error of timers of XGB series is ‘1 scan time + the time from 0 step to timer
instruction’
t1 2t0t
t
4
Timer input
condit
io
n
Ti
mer output
rel
ay
Preset
value
Current
val
u
e
t0
t1
t2
t
3
t
4
t0
t2
t0+PT t2+PT
t4+PT
t4
t0
T
t3
t0
+P
T
t2
t3
T
imer input
condi
ti
on
Ti
mer output rela
y
Preset valu
e (PV)
Current
value (E
T)
Set