317
SECTION 6
Program Execution Timing
The
timing of various operations must be considered both when writing and debugging a program. The time
required to ex
-
ecute
the program and perform other CPU operations is important, as is the timing of each signal coming into and leaving the
PC
in order to achieve the desired control action at the right time. This section explains the cycle and shows how to calculate
the
cycle time and I/O response times.
6-1 Cycle Time 318. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-2
Calculating Cycle T
ime 322. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-2-1 PC with I/O Units Only 322. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-2-2 PC with Link Units 323. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-3 Instruction Execution Times 324. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-4
I/O Response T
ime 333. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-4-1
Basic Systems
333. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-4-2
Remote I/O Systems
334. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-4-3
Host Link Systems
336. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-4-4
PC Link Systems
337. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-4-5 One-to-one Link I/O Response Time 339. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-4-6 Interrupt Response Times 341. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .