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ASM 421 Technical Description
6GT2 097-3AH00-0DA2
– 29 –
RD: 03/02
6GT2 002-0DA00
ASM 421 / V.24
Subject to change without notice!
6GT2 002-0DB00
ASM 421 / RS422
6GT2 002-0DC00
ASM 421 / TTY
J31069-D0142-U001-A0-7618
3.4.5
READ
Telegram to the file handler:
’R’
CC CI ADB DBN DBL
xx 00 0000
File name
Start addr.
Length
0
1
2/3
4
5
6/7
8/9
10
11/18
19/21
22/24
File name; 8 ASCII characters (20H-7EH)
Length of file data to be read (in bytes)
000000
→
The presence of the file in the directory is
checked. No data are transmitted to the
user. If the file is not present, an error
message results.
xxxxxx
→
The amount of data specified here is read
from the MDS. If the MDS does not
contain as much data as specified here,
the actual amount of data is transmitted
to the user in the DBL and a WARNING
is set in the status byte.
FFFFFF
→
If a length of –1 is passed, the file handler
reads the complete file. (The start
address must be given a value of
000000). The actual data length will be
passed to the user in the DBL parameter.
If a start address not equal to 000000 is
entered, the file handler reads the file
from the specified address to the end of
file.
Offset address within the file (hex).
A data file always begins at address 000000. If only a part of the file
is read in order to give rapid access to important MDS data, the start
address can be set here.
Important: The start address must lie within the bounds of the
existing file.
’I’
0001
0E
*
0001
*
* Important:
A value of 0001H must always be entered for the parameters ADB and DBN in the first
telegram of a read command. The file handler calculates the actual number of ADBs and
sends this to the user in the first acknowledgement telegram (see example on the next
page).
Acknowledgement:
’R’
CC Status ADB
DBN DBL
00
xx
0000
xxxx
0
1
2/3
4
5
6/7
8/9
10
0001
00
xx xx xx xx xx xx xx xx xx
xx
11/255
Data
DBL
The actual number of telegram segments for this read
operation is passed to the user here.