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3 Interface Modules
3.4.3 AS 512 protocol
•
Data word number (DW number)
The entry in the field DW number specifies the number of message frame data words to
be transmitted.
200 bytes are transmitted in the example, therefore 100 words = 0064
here.
•
Coordination flag (Ko-merk)
The entry in the coordination flag field specifies which flag is set in the destination system
after arrival of the message frame.
The destination device recognizes by means of this flag that a message frame has been
received.
In figure "AS 512 action message frame", for example, byte 6, bit 7 = 0607
entered.
•
Message frame data length (TEDA-L)
The message frame data length in bytes is specified again following the AP 512 header.
This length specification is not part of the AP 512 protocol. It indicates how many bytes
follow after this value. In the example, the data volume is 200 bytes (including TEDA-L),
therefore a value of 198 bytes =00C6
Response message frame (figure "AS 512 response message frame")
The response message frame is an acknowledgement at protocol layer. The protocol header is
split up into the identification and error number fields.
•
Identification
The identification field is three bytes long. The entry 00 00 00 means response message
frame.
•
Error number (E. no.)
In the case of a negative acknowledgement, an error number is entered in this field.
In figure "AS 512 response message frame" an error-free transmission is assumed,
therefore 00
is entered.
Hex
Subsequent message frame (figure "AS 512 subsequent message frame")
In the example, a subsequent message frame has to be sent. The protocol header of the
subsequent message frame is split up into the fields identification and job type.
•
Identification
The identification field is two bytes long. The entry FF00
message frame.
•
Job type
As with the action message frame, the job type has to be identified
here, and AD (ASCII)= 4144
Subsequent response message frame (figure "AS 512 subsequent response message
frame")
The subsequent response message frame structure is similar to that of the response message
frame. The protocol header contains the identification and error number fields.
•
Identification
The identification field is three bytes long. The entry FF 0000
subsequent response message frame.
•
Error number (E.no.)
Errors during transmission of the subsequent message frame are indicated in this field.
3–40
is entered in the TEDA-L field.
Hex
is entered.
Hex
© Siemens AG 1989 All Rights Reserved
are entered
Hex
has been
Hex
indicates a subsequent
Hex
identifies a
Hex
6FC5 197-0AB20-0BP0
SINUMERIK 840/880 (PJ)
06.91
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