Справочное Руководство для LXE 1280
E-SW-LDSPLUSRG-G
LDS Plus Reference Guide
Chapter 5 Expanded Functions
For The Programmer
The content of this chapter is directed to the programmer responsible for writing applications that
communicate with LXE LDS Plus DOS computers.
communicate with LXE LDS Plus DOS computers.
This chapter discusses expanded functions and provides guidelines for sending these messages to
the network devices and DOS computers.
the network devices and DOS computers.
Refer to Chapter 4, “Messages”, for descriptions of message structure, fields and elements.
Introduction
Note:
Expanded Functions are not applicable to Inbound or Protocol messages.
An expanded function is a special message that allows more extensive control over the DOS
terminal than is accomplished with a control character alone.
terminal than is accomplished with a control character alone.
CTRL and N/EF Characters
Control characters (located in the CTRL field) in an outbound message determine how an LDS
Plus terminal reacts to a message. Certain outbound CTRL characters also require an additional
character which is either a Number (N) or an Expanded Function (EF) code (N/EF).
Plus terminal reacts to a message. Certain outbound CTRL characters also require an additional
character which is either a Number (N) or an Expanded Function (EF) code (N/EF).
The N/EF character (located in the N/EF field of the message) provides additional control for a
message than just a control character alone. The control character determines whether an N/EF
character is required. It also determines whether the N/EF character represents a numeric quantity
or an expanded function.
message than just a control character alone. The control character determines whether an N/EF
character is required. It also determines whether the N/EF character represents a numeric quantity
or an expanded function.
This chapter focuses on the Expanded Function part of the N/EF field.
Refer to Chapter 4, “Messages”, section titled “Control Character (CTRL)”, for an explanation
and examples of the Number (N) portion of the N/EF code.
and examples of the Number (N) portion of the N/EF code.
Forced and Unforced Messages
Expanded functions initiated by the host provide a means of expanding the control capabilities of
the DOS computers. Expanded functions cannot be combined with any of the following:
the DOS computers. Expanded functions cannot be combined with any of the following:
• A programmed buffer length change.
• A programmed number of beeps.
• A programmed number of beeps.
The recommended Host format for a forced expanded function message is:
<IDSYExpandedFunctionC
R
L
F
If text is included in the message and if a message is already in the terminal’s Receive buffer, the
incoming message must be of the Forced type for the expanded function to take effect and the
Receive buffer to be overwritten by the text.
incoming message must be of the Forced type for the expanded function to take effect and the
Receive buffer to be overwritten by the text.