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Translate Option
Choices are None, Default, User (for transmit and receive), and Alternate.
Translation is specified separately for transmit and receive operations.
Most IBM hosts use EBCDIC (Extended Binary Coded Decimal Interchange Code)
and most asynchronous devices use ASCII (American National Standard for
Information Interchange). The 3708 provides two standard translation tables for
converting EBCDIC to ASCII and ASCII to EBCDIC; a default table and an
alternate table. See Appendix F, "IBM-Supplied Translate Tables" on page F-l for
more information. The default translation table causes the following unusual
translations:
If neither the default nor alternate translation tables meet the requirements for the
application, you may define a user-defined translate table. If no translation is
required, or the host application provides it, the 3708 has a no translation option for
protocol enveloping.
Notes:
1.
Until a session has been established, the 3708 uses the default translation table.
2. Configuration items, such as, line turnaround characters should be specified as
they would be seen at the host, after any specified translation is performed.
Turnaround Characters
Choices are X' 01' - X' FF' (for up to five different characters).
Each of the defined line turnaround (L T A) characters act as end of message
characters and tell the 3708 when the downstream device has finished data
transmission. When operating with an HDX control unit, once a receive operation
has begun, the 3708 does not begin the transmission of host data until line
turnaround has taken place. When operating on an HDX facility, these characters
should signal the physical line turnaround. The downstream device should drop
RTS when one of the LTA characters is transmitted. Although LTA characters are
not required for FDX control units, they are often used to signal the logical
end-of-message and cause the 3708 to forward data to the host.
When the 3708 receives a LTA character, any data in the current data buffer,
including the LTA character, is forwarded to the host. Commonly, carriage return
(CR X'OD') is used as a LTA character.
Note: LTA characters must be specified as they appear at the host. Received
characters are checked to see if they are LT A characters (after translation, if
specified).
Warning: To prevent the 3708 from being driven into buffer slowdown when
XONjXOFF
pacing is not supported, no more than three of the same LTA
character may be received consecutively. If TRANSMIT
XONjXOFF
is 0, the 3708
discards the additional L T A characters until it receives a character that is not a
turnaround character or a different turnaround character.
Chapter 5. 3708 Protocol Enveloping Mode
5-5
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