TN3270 Server Manual

TN3270 Server Manual—424097-001
5-1
5
CRT Communication Protocol
This section is divided into three parts.
•
CRT Mode describes the format of Telnet 3270 data in CRT mode.
•
AM3270 Mode on page 5-2 describes the application interface to the Guardian
TN3270 Server when it is configured to emulate AM3270.
•
SNAX/XF Mode on page 5-8 describes the applicable file system procedures for
running the Guardian TN3270 Server in SNAX/XF mode.
CRT Mode
The Guardian TN3270 Server windows in CRT mode use data buffers passed from an
application which contain standard 3270 buffer orders and text. The Guardian TN3270
Server does not examine the screen orders. Communications-related characters are
added or stripped depending on whether the data is inbound or outbound.
You can configure the Guardian TN3270 Server to run in CRT or ITI mode with a
SETMODE 8 call. See Section 6, ITI Communication Protocol
for more information
about running the Guardian TN3270 Server in ITI mode.
Message Format for Outbound Data
For outbound data, as shown in Figure 5-1, the buffer should contain only the textual
part of a screen, from the command character (CMD) through the end of the screen
orders and the text. The Guardian TN3270 Server adds an end-of-record indicator to the
end of the buffer.
Figure 5-1. CRT Protocol Message Format for Outbound Data
006CDT .CDD
Telnet
Specific
Telnet (TCP/IP)
3270
E
O
R
I
A
C
W
C
C
C
M
D
3270 Screen Orders
Application