Rockwell Automation 1771-VHSC , D17716.5.74 Very High S - Manual (Page 75)

Period/Rate and Continuous/Rate Examples E–4
Note: “Left over” pulses are pulses that occur that are not
divisible by the scaler. (i.e. With a scaler of 4, if 6 pulses occur
there are 2 “left over” pulses.)
The following example demonstrates the operation of the outputs in
Continuous/Rate mode of operation. Note that Y = time between
incoming pulses trailing edge to leading edge, A = output on value,
and B = output off value.
The examples shown assume that, at the least, the number of pulses
equal to the scalar value is occurring at the gate/reset pin.
1. A < 4MHz count and B <> 0 and A > B
Output on time = (4MHz count – A) 250ns + scaler (Y) +
(B)(250ns)
2. A > 4MHz count and B <> 0 and B < 4MHz count and A > B
Output on time = scaler(Y) + B(250ns)
3. A > 4MHz count and B <> 0 and B > 4MHz count and A > B
Output = On
4. A > 4MHz count and B = 0
Output = Off
5. A < 4MHz count and B = 0
Output on time = (4MHz count – A)250ns
6. A < B < 4MHz count and A <> 0
Output on time = (B – A)250ns
7. A < 4MHz count < B and A <> 0
Output on time = (4MHz count – A)250ns
8. (4MHz count < A < B) or (A < B and 4MHz count > B) and A
<> 0
Output = Off
9. (B > 4MHz count) or (B > 0 and 4MHz count = 999,999) and A
= 0
Output = On
10.B < 4MHz count and A = 0
Output off time = (4MHz count – B)250ns
Operation of Outputs in
Continuous/Rate Mode