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Pathway/iTS TCP and Terminal Programming Guide

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Programming for Specific Terminals
Compaq NonStop™ Pathway/iTS TCP and Terminal Programming Guide—426751-001
3-17
Using Intelligent-Mode Devices
Using Intelligent-Mode Devices
A SCREEN COBOL program operates in intelligent mode when it communicates with
an intelligent device. An intelligent device is any device that can receive and reply to
messages sent by the SEND MESSAGE statement in a SCREEN COBOL program. An
intelligent device could be a personal computer, an automatic teller machine, a point-of-
sale device, a Guardian operating environment process, a communications line, or a
6540 terminal operating as a personal computer.
When writing a program to communicate with such a device, you should be aware of the
following:
•
The SCREEN COBOL program has no control over the device. It is up to the
person writing code for the device to start up the device; accept any messages from
the SCREEN COBOL program; send any replies back to the SCREEN COBOL
program; supply the operator interface, if any; and so forth.
•
The SCREEN COBOL program is responsible for synchronizing messages between
the program and the intelligent device. The program must check for duplicate
messages from the device.
•
Pathway/iTS does not establish modem connections for intelligent devices. If you
want a modem connection, you must use the RECONNECT MODEM statement.
•
The TCP does not collect messages for intelligent devices in a buffer as it does for
data sent to a terminal screen. Each message is sent when the SEND MESSAGE
statement is executed.
•
The Message Section provides some formatting of data sent to and received from an
intelligent device. When data is passed directly between the intelligent device and
data areas in the Working-Storage or Linkage Sections, it is not formatted.
•
Programs that communicate with intelligent devices cannot use the following
SCREEN COBOL statements:
ACCEPT RESET
CLEAR INPUT SCROLL
DISPLAY SET NEW-CURSOR AT
DISPLAY BASE TURN
DISPLAY OVERLAY USE FOR SCREEN RECOVERY
DISPLAY
RECOVERY
USE FOR TERMINAL-ERRORS
PRINT SCREEN