CPU Specifications
and Operation
4–19
CPU Specifications and Operation
The CPU processes the program from address 0 to the END instruction. The CPU
executes the program left to right and top to bottom. As each rung is evaluated the
appropriate image register or memory location is updated. The time required to
solve the application program depends on the type and number of instructions used,
and the amount of execution overhead.
Just add the execution times for all the instructions in your program to determine to
total execution time. Appendix C provides a complete list of the instruction execution
times for the DL05 Micro PLC. For example, the execution time for running the
program shown below is calculated as follows:
X0
X1
Y0
OUT
C0
C100
LD
K10
C101
OUT
V2002
C102
LD
K50
C103
OUT
V2006
X5
X10
Y3
OUT
END
Instruction
Time
STR X0
2
m
s
OR C0
1.6
m
s
ANDN X1
1.6
m
s
OUT Y0
6.8
m
s
STRN C100
2.3
m
s
LD K10
42.7
m
s
STRN C101
2.3
m
s
OUT V2002
16.6
m
s
STRN C102
2.3
m
s
LD K50
42.7
m
s
STRN C103
2.3
m
s
OUT V2006
16.6
m
s
STR X5
2
m
s
ANDN X10
1.6
m
s
OUT Y3
6.8
m
s
END
24
m
s
SUBTOTAL
174.2
m
s
Overhead
DL05
Minimum
0.66 mS
Maximum
2.5 ms
TOTAL TIME = (Program execution time + Overhead) x 1.1
The program above takes only 174.2
m
s to execute during each scan. The DL05
spends 0.1ms, on internal timed interrupt management, for every 1ms of instruction
time. The total scan time is calculated by adding the program execution time to the
overhead (shown above)and multiplying the result (ms) by 1.1. “Overhead” includes
all other housekeeping and diagnostic tasks. The scan time will vary slightly from
one scan to the next, because of fluctuation in overhead tasks.
Program Control Instructions
— the DL05 PLCs have an interrupt routine feature
that changes the way a program executes. Since this instruction interrupts normal
program flow, it will have an effect on the program execution time. For example, a
timed interrupt routine with a 10 mS period interrupts the main program execution
(before the END statement) every 10 mS, so the CPU can execute the interrupt
routine. Chapter 5 provides detailed information on interrupts.
Application
Program Execution
Содержание DL05
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Страница 436: ...1B DL05 Error Codes In This Appendix Ċ Error Code Table ...
Страница 443: ...1C Instruction Execution Times In This Appendix Ċ Introduction Ċ Instruction Execution Times ...
Страница 459: ...1D Special Relays In This Appendix Ċ DL05 PLC Special Relays ...
Страница 464: ...1E DL05 Product Weights In This Appendix Ċ Product Weight Table ...
Страница 466: ...1F European Union Directives CE In This Appendix Ċ European Union EU Directives Ċ Basic EMC Installation Guidelines ...