SNAX/APN Application Programming Manual

The CRT Interface
SNAX/APN Application Programming Manual—420111-001
2-8
Summary of the Three CDI Modes
Table 2-1. Differences Between Normal, Special, and Enhanced CDI Modes
Normal CDI Mode Enhanced CDI Mode
Special CDI
Mode
SETMODE (163,0) (163,1) (163,2)
CALL READ If part of a two-step read:
Get the data from SNAX/APN.
If not part of a two-step read:
From SEND state:
Send (Null RU, CDI).
From RECEIVE state:
Do nothing.
Note that READ may be issued
with or without first issuing a
WRITEREAD (filenum, 0,
2).
Same as normal CDI
mode
A READ is
allowed only as
part of a
two-step read.
CALL WRITE If the 3270 data stream is one
of the following:
• READ
• READ MODIFIED
• READ MODIFIED ALL
CDI.will be set
Otherwise, CDI.will not be set
Same as normal CDI
mode, with one
addition:
If the WCC has the
keyboard restore bit
enabled AND the 3270
data stream is one of
the following:
• WRITE
• ERASE/WRITE
• ERASE/WRITE
ALTERNATE
• WSF: OUTBOUND
TEXT HEADER
• WSF: OUTBOUND
3270 DATA STREAM
• WSF: PRESENT
ABSOLUTE FORMAT
• WSF: PRESENT
RELATIVE FORMAT
CDI will be set.
Same as
normal CDI
mode
CALL
WRITEREAD
Only valid as WRITEREAD
(filenum, countbuffer, 0,
2).
This is the first step of a
two-step read, and a null RU
with CDI is sent.
Same as normal CDI
mode
WRITEREAD
is supported;
CDI is set on
the RU with the
outbound data.