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ASM 421 Technical Description
6GT2 097-3AH00-0DA2
– 11 –
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
ASM 421 interface modules can only be daisy-chained if they are using an RS422 or TTY interface. This
allows up to 16 interface modules to be driven from one serial interface.
The computer/PC must have a digital input (DI) and a digital output (DO) for each ASM 421.
Mode of operation:
Programming the ASM:
The computer/PC “selects” the module and then sends it the task telegram.
Command processing:
The ASM then processes the command. How long this takes depends on the command and can
last any amount of time (when there is no MDS in the field).
Send result to user:
By setting the “Request” flag, the ASM indicates that it wants to send a telegram. The computer/PC
recognizes this and “selects” the module. The selected ASM then sends the result telegram.
Task telegram
to ASM
Response
telegram from ASM
t
2
t
5
t
4
t
2
t
1
t
3
Data
Request
Select
t
1
100 ms
:
Wait time from select until data transmission.
t
2
0
:
Wait time from data transmission until deselection of ASM 421
t
3
Depends on
:
Processing of user command by the ASM 421
command
t
4
0
:
Time from “request active“ until selection of ASM 421
**
*
Select interrogate
t
5
=
0 ... 30 ms
:
Time from selection of the module until transmission of the result telegram
Important:
*
At the result telegram the ASM only interrogates the “select” at the beginning of a
transmission. If the “select” is deactivated during transmission of the telegram, the
ASM will nevertheless send the complete telegram to the computer.
This ensures that no garbled telegrams from the ASM are transmitted.
**
The select line must be set high for the entire time that an outgoing telegram is being
sent.