Chapter 6. Serial I/O, SNP & RTU Protocols
GFK-2222AD April 2018 219
6.2.12 Autodial Function (4400)
This feature allows the CPU to automatically dial a modem and send a specified byte string.
To implement this feature, the port must be configured for Serial I/O. After the autodial function is
executed and the modem has established a connection, other serial I/O functions (Write bytes, Set Up
Input Buffer, Flush Input buffer, Read port status, Write port control, Read bytes, Read String, and Cancel
Operation) can be used.
Example
Pager enunciation can be implemented by three commands, requiring three COMMREQ command
blocks:
It is the responsibility of the application program to hang up the phone connection.
This is accomplished by reissuing the autodial command and sending the hang up
command string.
Autodial Command Block
The Autodial command automatically transmits an Escape sequence that follows the Hayes convention.
If you are using a modem that does not support the Hayes convention, you may be able to use the Write
Bytes command to dial the modem.
Examples of commonly used command strings for Hayes-compatible modems are listed below:
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