Allen-Bradley 1747-OC Series, User Manual

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1747-UM001A-US-P - March 2000
1-4 Introducing the Open Controller
Your application (the code you develop) uses the dual-port memory to
communicate with the SCANNER and to handle control functions on the
1746 backplane, such as:
•
SCANNER commands and responses
•
battery and SCANNER status
•
scan rate frequency and timing
•
I/O image counters
•
priority messages and interrupts
•
semaphores to ensure data integrity
•
software-generated watchdogs
•
control of the four user-definable LEDs, the 3-position switch, and the
2-position jumper
The SCANNER functionality of the dual port supports I/O control
functions, such as:
•
synchronizing scans to the application
•
forcing I/O
•
discrete-input interrupts
•
I/O module-driven interrupts (such as for the 1746-BAS module)
•
I/O slot enables and disables
•
I/O resets
In addition to providing access to the control SCANNER, the dual-port
memory also provides non-volatile storage for:
•
I/O values
•
application parameters (timers, counters, presets)