Cpu Processing Modes - Omron CJ - PROGRAMMING MANUAL 08-2008 Programming Manual

CPU Processing Modes

6-8

CPU Processing Modes

6-8-1

CPU Processing Modes

Normally, peripheral servicing (see note) is performed once at the end of each
cycle (following I/O refresh) either for 4% of the cycle or a user-set time for
each service. This makes it impossible to service peripheral devices at a rate
faster than the cycle time, and the cycle time is increased by the time required
for peripheral servicing.
With CS1D CPU Units for Single-CPU Systems or with CS1-H or CJ1-H CPU
Units, however, Parallel Processing Modes are supported that enable pro-
cessing program execution in parallel with peripheral servicing. These modes
enable faster peripheral servicing and shorter cycle times, especially when
there is extensive peripheral servicing required. (CS1D CPU Units for Duplex-
CPU Systems and CJ1M CPU Units do not support the Parallel Processing
Modes.)
Note Peripheral servicing includes non-schedule services required by external
devices, such as event servicing (e.g., communications for FINS commands)
for Special I/O Units, CPU Bus Units, and Inner Boards (CS Series only), as
well as communications port servicing for the peripheral and RS-232C ports
(but not including data links and other special I/O refreshing for CPU Bus
Units).
Normal Mode
Overseeing processing
Program execution
I/O refreshing
Peripheral Servicing
Parallel Processing Modes
Program Execution Cycle
Overseeing processing
Program execution
I/O refreshing
Cycle time
Peripheral Servicing Cycle
Overseeing processing
Peripheral servicing
Cycle time for
program execution
Section 6-8
Cycle time for
peripheral servicing
341