α
2 Simple Application Controllers
Function Blocks 6
6 - 87
6.31
Random One Shot Block
This Function Block is equivalent to the One Shot function block except that the new block has
only randomly generated pulse time. An Upper and Lower Time Limit value can be set in
increments of 10 ms (0.00 to 327.67 seconds), 100 ms (00.0 - 3267.7 seconds), and 1 second
(0 - 32767 seconds) for the random number generation. If the Input signal turns Off during the
pulse interval, the Output is Reset along with the pulse time.
Table 6.45: Random One Shot function block
Note: The set time cannot be less than one scan time for the controller; otherwise, the
Random One Shot Function Block will not perform its assigned task for the time
specified. Users can monitor the scan time from the
α
2
Series Controller. Scan time
is dependent on the user- program; therefore, caution is needed as and when time
units are selected.
Setup of the Random One Shot Function Block directly from the
α
2
Series Controller
1 ) Allocate the input pin to be used for the function block.
2 ) Press the “OK” key with the cursor in the function block.
The function block edit screen is displayed as shown.
Function
Set Item
Description
I
Input pin for the random one shot function block
C
Clear pin for the random one shot function block
FB
1) A random one shot time is generated between the upper and lower
threshold values.
2) The random value only occurs in correlation to the ON status of the
input.
3) The clear signal input reset the output, random one shot value and
current time.
4) If the Upper threshold is equal to or larger than the lower threshold,
the random one shot time is set in the range lower threshold to upper
threshold.
5) If the Upper threshold is less then than the lower threshold, the
random one shot time is set in the range 0 to upper threshold or lower
threshold to 32767.
6) If the lower threshold = Upper threshold, the random one shot is
equal to the upper threshold = lower threshold.
7) Time units: 10ms, 100ms or 1s (*Note)
Output
1) The following items are available for other function blocks:
a) Random One Shot value
b) Current One Shot value
0
0
0
O
R
O
I
S
C
P
T i me
u n i
B 0 0 1 : R
C h a n g e N o
D e l e t e
F B
S
O
t
S e t u p
F B
