Cpu Unit Operation; General Flow - Omron CJ - 09-2009 Operation Manual

CPU Unit Operation

10-1 CPU Unit Operation

10-1-1 General Flow

Normal Mode
Cycle time
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 Units.
Automatically transfer
data from Memory Card.
Overseeing
Check the Battery.
processing
Check for Memory Card
and other devices.
Read DIP switch
settings.
Program
Operation processing: Execute the user program.
execution
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
Refresh data for the following
(even in
Units.
PROGRAM
Basic I/O Units
mode)
Special I/O Units (both words
allocated in CIO and DM area
and specific data for each Unit)
CPU Bus 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.
Peripheral port servicing
RS-232C port servicing
File access servicing
Communications port
servicing
Section 10-1
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