Scan Theory
Chapter 8
8-4
Add the execution values for each instruction by using Table 8.A. The
sum of these values added to the I/O scan time is the average scan time.
Table 8.A
These Are the
Approximate Execution Time Per Scan
(in
average
microseconds) and Words Per Scan for Each
Instruction
Instruction
Instruction Name
Symbol
True
average
µ
sec.
False average
µ
sec.
Words Per
Instruction
These instructions are features of the MiniPLC2/02, MiniPLC2/16, and MiniPLC2/17
Examine On
Examine Off
Output Energize
Output Latch
Output Unlatch
-[ ]-
-[ / ]-
-( )-
-(L)-
-(U)-
7
5
8
7
7
10
10
10
10
10
6
5
8
6
6
10
10
10
10
10
1
1
1
1
1
1
1
1
1
1
Get
Put
Equal
Less Than
Get Byte
Limit Test
-[G]-
-(PUT)-
-(=)-
-(<)-
-]B[-
-]L[-
15
12
12
14
11
13
10
10
10
10
10
10
-
7
13
13
-
14
10
10
10
1
1
1
1
1
1
1
1
1
1
1
1
Counter Reset
Retentive Timer Reset
Timer OnDelay
Retentive Timer OnDelay
Timer OffDelay
Up Counter
Down Counter
-(CTR)-
-(RTR)-
-(TON)-
-(RTO)-
-(CTD)-
-(CTU)-
-(CTD)-
19
19
51
52
55
38
36
6
6
36
33
39
30
31
1
1
1
1
1
1
1
add 1 word per instruction when its address is 400
8
or greater
add 2 words per instruction when its address is 400
8
or greater
1 word
999 words
1 bit
999 bits
with 2 data values
with 10 data values
with 50 data values
add 8
µ
s per instruction when its address is 400
8
or greater
add 16
µ
s per instruction when its address is 400
8
or greater
1
2
3
4
5
6
7
8
9
10
11
