4-50
Protection and Control
BE1-951
D2863-07.vsd
10-11-99
B L K
INI
0
1
0
0
1
1
t2
t1
x62
Figure 4-35. Mode 6, 1-Shot Nonretriggerable Latch
D2843-12.vsd
02-02-99
0
1
0
1
0
1
BLK
INI
x62
Timer
100%
0 %
t1
t1
t2
t2
Figure 4-34. Mode 5, Integrating Timer
the initiate expression toggles to FALSE and the
timer starts resetting at twice the rate as it was
integrating toward time out. It stays FALSE long
enough for the integrating timer to reset
completely; but, then toggles back to TRUE and
stays TRUE for the entire duration of time T1. At
that point, the output of the timer is toggled to
TRUE. Then at some time later, the initiate
expression becomes FALSE and stays FALSE for
the duration of RESET time T2. At that point, the
output of the timer is toggled to FALSE.
This type of timer is useful in applications where a
monitored signal may be hovering at its threshold
between on and off. For example, it is desired to
take some action when current is above a certain level for a certain period of time. A 50T function could be
used to monitor the current level. Thus, if the current level is near the threshold so that the initiate toggles
between TRUE and FALSE from time to time, the function will still time out as long as the time that it is
TRUE is longer than the time that it is FALSE. With a simple PU/DO timer, the timing function would reset
to zero and start over each time the initiate expression became FALSE.
Mode 6, Latch
A one-shot timer starts its timing sequence when
the initiate expression changes from FALSE to
TRUE. The timer will time for DELAY time T1 and
then the output will latch TRUE (see Figure 4-35).
Additional initiate input expression changes of
state are ignored. Time (T2) is ignored.
BESTlogic Settings for 62/162 General Purpose Logic Timers
The logic settings for the 62/162 timer functions are listed in Table 4-40. These settings enable the element
by selecting the mode of operation and providing initiate and blocking control as determined by the logic
expressions assigned to those inputs.
Table 4-40. 62/162 BESTlogic Settings
Function
Range/Purpose
Default
Mode
0 = Disabled
3 = 1 Shot Retriggerable
1 = Pickup/Dropout
4 = Oscillator
2 = 1 Shot Nonretriggerable
5 = Integrating
6 = Latch
0
Initiate Logic
Logic expression that initiates timing sequence.
0
BLK Logic
Logic expression that disables function when TRUE.
0
BESTlogic settings for the 62/162 element can be made using the SL-x62 (settings logic-timer) command.
