IBM 5251 Series Maintenance Information Manual page 184

Read Data Word
Bits 0 2 3 4 5 6 7 8 9 10 11 12 13
I I
Fill bits
l
Station
P
8
4 2
(always 0001 Address Character
Parity
Last
Error
Data
Bit 7
o
= Reader not installed
1 = Reader installed
Bit 8
0= No error
1 = Reader error
Bit 9
o
= Not last character
1
=
Last character
Valid Codes for the Character Field
Hex
Code
P
0
1
1
0
2 0
3
1
4 0
5
6
1
7
0
8 0
9
A 1
B 0
C 1
0 0
E 0
F
8
0
0
0
0
0
0
0
0
Bits
4 2
o
o
o
o
1
o
o
o
o
o
o
1
o
o
1
o
o
o
o
o
o
1
o
1
o
o
1
o
o
1
o
Character
o
1
2
3
4
5
6
7
8
9
% (start of
message (SOM
I)
@
--,
?
(end of
message (EOMn
5-4
14 15
l
Sync
The first character sent in the read data / activate read
command sequence is the SOM; it is followed by up to
15 data characters. If one of the read data words in
this sequence does not contain EOM in the character
field, the controller sends another read data
command/activate read command sequence. After this
command sequence has been received at the MSR,
another 16 read data words are sent to the adapter.
This sequence continues until the EOM occupies the
character field of one of the read data words. When the
EOM is sent to the adapter, an LRC (longitudinal
redundancy check) character is sent in the next read
data word to check the validity of the data transfer.
Eight read data / activate read command sequences are
required to send the maximum of 128 bytes.