ASM 421 Technical Description
6GT2 097-3AH00-0DA2
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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
5.7
Diagram showing possible MDS states at an SLG
The following codes are used in the diagram on the following page:
MD
MDS absent
MDN
new/next MDS present
MDA
current or old (no longer current) MDS present
BD
Command present (the user has already transmitted an MDS command to the MDS)
BD
Command not present (the ASM is not processing an MDS command from the user)
BIA
Command in progress (a command is now being executed)
ND
“Next MDS bit” set in the file handler (the ASM has received a NEXT command from the
user).The processing of all subsequent commands takes place only with the next/new
MDS.
ND
“Next MDS bit” not set in the file handler (the ASM has not yet received a NEXT
command).
File handler action
Status at an SLG station.
ÇÇÇ
ÇÇÇ
Two process sequences will be described as examples:
A
EAKO = 0; an MDS is present in the transmission window of the SLG on restart. The file “switch” is
to be read dynamically by the SLG. The computer sets a switch (points) and then waits for the next
MDS.
1.
After a Restart and a RESET command from the user, the file handler writes the SLG no. to the
MDS and goes into status 3 . ANW bit = 1.
2.
The user sends the READ “switch” command to the ASM. The file handler starts the com-
mand and changes to status 27 .
3.
After executing the command, the ASM sends the data it has read and goes into status 3 .
4.
After evaluating the data the user sets a switch (points). The MDS has meanwhile left the
transmission window of the SLG: status 5 ; ANW bit = 0
5.
The user sends a NEXT command: status 11 . The processing of the MDS is now complete.
6.
Immediately after the NEXT command, the user sends the command READ “switch”. The
command is temporarily stored in the ASM: status 23 . This status remains until a new MDS
enters the transmission window of the SLG.
7.
A new MDS enters the transmission window of the SLG: ANW bit = 1. The file handler begins
processing immediately: the SLG number is written to the MDS and the execution of the com-
mand READ “switch” initiated: status 27 .
8.
This point is identical to point 3. The MDS processing cycle restarts from the beginning.
Status diagram for this application, provided no error occurs:
3
27
3
5
11
23