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6GT2 097-3AH00-0DA2
Example:
You want to know how much time elapses from the start of a read operation until the data is in the PC
memory. The file to be read has a length of 350 bytes and is to be transmitted in 2 blocks. The maximum
block length to the PC is 255 bytes. The mobile data carrier is an MDS 505 (32 kB). It is in the transmission
window of the SLG. The data rate between PC and ASM is 4800 baud.
The command sequence can be divided into the following time slices:
Description
1)
Issuing the read command and start of command by the 3964R
driver in the PC
2)
Transmission of the command to the ASM:
25 user bytes + 6 procedure bytes
(response times in PC set to zero)
3)
File handler processing time
4)
Processing time of the MDS by the file handler
a) on the first occasion, when the MDS directory does not yet exist
in the ASM
b) reading of 244 bytes file data (60 ms + n * 1 ms)
5)
Transmission of data to the PC:
(244 + 11) bytes user data + 6 procedure bytes
(the acknowledgement times in the PC are set to zero)
6)
Processing time in the PC and issuing the second command seg-
ment to the 3964R driver
7)
Transmission of the second command segment to the ASM:
11 user bytes + 6 procedure bytes
(response times in PC set to zero)
8)
File handler processing time
9)
Processing time of the MDS by the file handler:
Reading of 106 bytes (n * 1 ms)
(Reading the directory is definitely no longer necessary; the con-
stant time for the processing of the system area of an MDS is not
required for each subsequent command segment)
10) Transmission of data to the PC:
(106 + 11) bytes user data + 6 procedure bytes
(acknowledgement time in the PC is set to zero)
11) Processing time in the PC until the data is available to the user
Total time of the read operation
(the times of the PC are set to zero;
the directory already exists on the ASM)
– Read times between ASM and MDS
– Communications between PC and ASM
Subject to change without notice!
RD: 03/02
J31069-D0142-U001-A0-7618
ASM 421 Technical Description
6GT2 002-0DA00
– 60 –
6GT2 002-0DB00
6GT2 002-0DC00
See diag.
Time in ms
page 59
Application
A
71
B
––
C
(940)
D
304
B
600
Application
A
39
B
C
––
106
D
283
B
Application
A
1403
410
993
ASM 421 / V.24
ASM 421 / RS422
ASM 421 / TTY
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