Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual - Manual (Page 122)

Timer and Counter Instructions
Chapter 5
5Ć24
The execution time, T, in microseconds for the complete mode is:
T = 99 + 9.8 (Words operated upon per scan) + 14.4 (Number of 256
word blocks operated upon per scan)
Example: What is the execution time to perform a File-to-File AND
operation on two files 670 words long? The rate per scan is 256 and the
mode is the distributed complete mode.
T = 125 + 9.8(256) + 14.4(2) = 125 + 2509 + 28.8 = 2663
T = 2663 microseconds = 2.66 milliseconds.
The incremental mode requires approximately 100 microseconds per scan.
When the instructions are false, they require 6 microseconds.
The first scan the rung is false after the done bit is set requires 17.6
microseconds to reset flags and counters.
Table 5.G
Average Execution Times In Microseconds For FILEĆTOĆFILE AND, OR,
XOR Instructions When Instruction Is TRUE
Time (Microseconds)
Rate (Words per Scan) Dist. Complete Mode Complete Mode
ăă5
ă10
ă15
ă25
ă50
100
256
512
ă174
ă223
ă272
ă370
ă615
1105
2648
5171
ă148
ă197
ă246
ă344
ă589
1079
2622
5145
Formulas for more exact approximations can be found in Section 5.6.4.
Execution time for Incremental mode is 100 microseconds per scan. When FALSE, execution time is 6 microseconds. Time
required to reset flags and counters is 17.6 microseconds.