Rockwell-automation 1747-PCINT API Software for 1746 I/O Manuel d'utilisateur télécharger pdf (Page 12)

1–4 Overview

Publication 1747-6.5.3 June 1998

Your application (the code you develop using the API) uses the dual port memory

to communicate with the scanner 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 4 user-definable LEDs, the 2-position jumper, and the 3-

position switch

The scanner functionality of the dual port supports I/O control functions, such as:

• synchronizing scans to the application

• forcing I/O

• defining discrete-input interrupts

• defining I/O module-driven interrupts (such as for the 1746-BAS module)

• enabling and disabling I/O slots

• resetting I/O

In addition to providing access to the control scanner, the dual port memory also

provides non-volatile (optional battery-backed) storage for:

• I/O values

• application parameters (timers, counters, presets)

Scanner Modes The scanner CPU operates in six basic modes:

• performing POST (power-on self test)

• waiting for host initialization

• Idle

• Scan

• Faulted

• non-recoverable fault

After the scanner successfully completes the POST, the scanner waits for an

initialization complete command from the application. Once the scanner receives

this command, the scanner enters Idle mode.

Before the scanner can enter Scan mode, the application must download a valid

I/O configuration to the scanner.

If a recoverable fault occurs, the scanner enters Faulted mode. Use the

OC_ClearFault API function to clear the fault before the scanner can resume

operating in Scan mode.

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Rockwell-automation 1747-PCINT API Software for 1746 I/O Manuel d'utilisateur Page 12