Cutler-Hammer D320 PLC, Руководство пользователя

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D320 PLC User's Manual
Operation mode and function according to CPU mode switch
Mode Change
Switch
Operation
Mode
LED Display
Run Prog.
Program
Change
Data Change Initialize
Switch
Mode after
Power-Cycle
Run Disabled Enabled × Run
Run
Stop Enabled Enabled × Run
Run Enabled Enabled × Run
Remote
Pause Enabled Enabled × Pause
Prog Stop Enabled Enabled Stop
•
When the Prog. LED is on, you can change the user program.
•
The Initialize switch clears errors when the mode switch is set to Prog.
•
When the mode switch is set to Remote and power is switched from Off to On, the previous
mode of operation is restored.
•
When debugging the user program, the mode switch should be set to Remote.
CPU Processing Procedure
Program Processing Procedure
The diagram indicates the PLC program processing procedure. The CPU regularly repeats procedure 1
through 5. This cycle is called 1 scan time.
1. Mandatory input/output processing
The internal force table is applied to internal/external I/O, turning forced I/O On or Off.
2. Input/output processing
Preserves the On/Off state of the external I/O and uses it as input in the next scan. (For
accurate processing, input should continue for more than 1 scan time.) The processed program
outputs are sent from the internal memory to the external modules.
3. Watchdog time initialization
The watchdog elapsed time value is set to 0. This value is the watchdog calculation point until
the next scan.
1. Mandatory
input/output
2. Process
input/output
3. Watchdog
time
→
0
4. Program
analysis
5. Peripheral device
signal processing
1 scan
time