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C-6_0-007-00_836905_E_0704.p65
37
Description of
Various Protocol
Variants
38
Read from data carrier with head select and block size
Write to data carrier with head select and block size
Task
Data Flow Com-
mand
from host
'L'
Read
system to
BIS
from BIS
to host
system
from host
'P'
Write
system to
BIS
from BIS
to host
system
1) The commands Status and/or Quit are not permitted at this point.
2) Instead of block check BCC, depending on protocol variant either Carriage Return 'CR' or LIne Feed with Carriage Return may be used.
3) <ACK> '0' is returned as acknowledgement if there is no error, or <NAK> + 'Error No.' if an error occurs.
4) For protocol variants which always require a terminator, either 'CR' or 'LF CR' must be inserted here as a terminator.
Data within angle brackets are control characters.
Values inside apostrophes represent the respective character(s) in ASCII code.
38
english
Programming
Reference is now made to the command string 'L 0013 0128 20 G' with 'G' as BCC (see
preceding page). This command string is here shown in its possible variants; also shown are
the various forms of acknowledgement with and without terminator:
Command line from
host system to BIS
with BCC,
but no terminator
'L 0013 0128 20 G'
with 'CR' instead of BCC,
no terminator
'L 0013 0128 20 CR'
no BCC,
with terminator 'CR'
'L 0013 0128 20 CR'
no BCC,
with terminator 'LF CR'
'L 0013 0128 20 LF CR'
For <NAK> with error number a '1' was used here (no data carrier present) as an error ex-
ample.
The respective positions for the additional terminator are shown in the tables in italics.
Programming
Start address
Number of
Head
Block
End
of first byte to
bytes to be
No.
size
2)
be sent
sent
A3 A2 A1 A0
L3 L2 L1 L0
K
B
BCC
'0 0 0 0'
'0 0 0 1'
'1' or
'0' or
or
to
to
'2'
'1'
see
'8 1 9 1'
'8 1 9 2'
2)
1)
A3 A2 A1 A0
L3 L3 L1 L0
K
B
BCC
'0 0 0 0'
'0 0 0 1'
'1' or
'0' or
or
to
to
'2'
'1'
see
'8 1 9 1'
'8 1 9 2'
2)
1)
Acknowledge from BIS
for correct reception
No terminator
<ACK> '0'
No terminator
<ACK> '0'
with terminator 'CR'
<ACK> '0 CR'
with terminator 'LF CR'
<ACK> '0 LF CR'
Acknow-
Termi-
Start
Termi-
Data (from start
ledge
nator
trans-
nator
address to start
3)
4)
mission
4)
address
+ no. of bytes)
<STX>
'CR' or
'LF CR'
<ACK>'0'
'CR' or
D1 D2 D3 ... Dn
or <NAK>
'LF CR'
+ Error-
No.
1)
<STX>
D1 D2 D3 ... Dn
<ACK>'0'
'CR' or
or <NAK>
'LF CR'
+ Error-
No.
Acknowledge from BIS
for incorrect reception
No terminator
<NAK> '1'
No terminator
<NAK> '1'
with terminator 'CR'
<NAK> '1 CR'
with terminator 'LF CR'
<NAK> '1 LF CR'
37
english
End
Acknow-
Termi-
2)
ledge
nator
3)
4)
BCC
or
see
2)
BCC
or
see
2)
<ACK>'0'
'CR' or
or <NAK>
'LF CR'
+ Error-
No.
1)
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