General Flow For Single Cpu Systems - Omron CS1D DUPLEX SYSTEM - 10-2009 Operation Manual

CPU Unit Operation
9-1-2

General Flow for Single CPU Systems

Normal Mode for Single CPU Systems
Cycle time
330
The following flowchart shows the overall operation of the CPU Unit.
Note The CPU Unit's processing mode is set to Normal Mode, Parallel Processing
with Synchronous Memory Access, or Parallel Processing with Asynchronous
Memory Access in the PLC Setup (Programming Console address 219, bits
08 to 15). This setting is also possible from the CX-Programmer.
In the normal mode, the program is executed before I/O is refreshed and
peripherals are serviced. This cycle is executed repeatedly.
Power ON
Startup
initialization
Initialize hardware
memory and system work
area.
Detect I/O.
Automatically transfer data
from Memory Card.
Overseeing
Check the Battery.
processing
Check for Memory Card
and other devices.
Read DIP switch settings.
Program
execution
Operation processing: Execute the user program.
Error processing: Turn OFF outputs. (Reset Units
for bus errors.)
After error: Clear I/O memory is an error occurs
(unless a FALS(007) instruction created the error).
I/O refreshing
(even in
Refresh data for the following
PROGRAM
Units.
mode)
Basic I/O Units
SYSMAC BUS Remote I/O Master
Units
Special I/O Units (both words
allocated in CIO and DM area and
specific data for each Unit)
Peripheral
servicing
Perform the following
servicing if any events have
occurred.
Special I/O Unit event
servicing
CPU Bus Unit event servicing
Verify actual Units with
registered I/O tables.
Clear I/O memory.
Check user memory.
Clear forced status, etc.
Check I/O bus.
Check user program
memory.
CPU Bus Units (both words
allocated in CIO and DM area and
specific data for each Unit)
Inner Boards (both words
allocated in CIO and DM area and
specific data for each Unit)
Peripheral port servicing
RS-232C port servicing
Inner Board event servicing
File access servicing
Communications port
servicing
Section 9-1