Intermec CK30

Display Data Stream—Chapter 6
295TE 2000
 5250 Terminal Emulation Programmer’s Guide
Asynchronous 5250 Prefixes
Each asynchronous 5250 data stream command is preceded by a variable-
length prefix. The first byte of the prefix contains the number of bytes in
the prefix, not including the length byte. The length may be zero, which
indicates an empty prefix. The second byte of the prefix (if the length is
nonzero) must be either hex 40 or C0.
S Hex 40 indicates that the data in the rest of the message is LU-LU (nor-
mal 5250 commands).
S C0 indicates that the rest of the message is SS-LU data (an SS message).
SS messages cause the terminal to enter the SS message state, where the
only allowable keystroke is Reset. The SS message is a one-line message
that is displayed on the terminal’s status line until the Reset key is
pressed.
After hex 40 or C0, the 5250 prefix may contain one 5250 signal. A signal
is a sequence of 5 bytes that tells the terminal to perform a special opera-
tion. The terminal supports the Signal command formats in the following
chart.
Hex Code Description
C9 00 00 00 01 Signal operator (turns on the Message Waiting annunc iator and
sounds the audible alarm)
C9 00 00 00 05 Resets the Message Waiting annunciator
A parameter error is posted when less data is in the message than indicated
by the length byte. This causes a parameter error of “21.” If the terminal
encounters data it does not understand, it ignores the rest of the prefix.