Table of Contents
Advertisement
6 Message Frames
6.6 Addressing
6.6
Addressing
Bus connection and connection via serial interface feature a similar addressing concept. The
only differences are in the interpretation of the procedure and protocol header data on the
respective interface module. The addressing via message frames is identical with both
connections if the serial interface is configured with "with system 800 ID". In the following, the
addressing philosophy shall be explained by means of a message frame which is transferred to
the user interface. The figure "Addressing" shows schematically the route of the message
frame and the evaluation of the message frame headers.
The information of the lower OSI layers is contained in the procedure header of the message
frames. With the bus interface, these are the Ethernet and TSAP address on the basis of
which the message frame is routed through the local area network to the interface module, up
to layer 4. In the procedure header for the serial interface module, addresses are not
necessary since an unambiguous hardware allocation is made by the interface used.
Logical partners are assigned to the address information in the protocol header on the
interface module. In case of the bus interface module, this is done by the AP monitor whereas
in case of the serial interface module the device management is responsible for this task. The
necessary information is stored in lists.
If no protocol header is configured for a serial interface (without AS 512 protocol) the logical
partner is determined solely by the information from the addressing list (interface number
logical partner). In this case there is only one logical partner per interface. The logical partner
recognized from the address information is transferred to the dual port RAM. The procedure
header and the protocol header completely terminate on the interface module on input and are
generated on the interface module on output.
The SINUMERIK driver takes over the remaining addressing including the entry in the dual port
RAM. In the case of bus connections and serial connections which are configured with System
800 identification, the SINUMERIK driver generates the function number from the first 6
characters of the identification. It evaluates the remaining SINUMERIK-specific address
information on the basis of allocations stored in lists and enters the data in dual port RAM.
If a serial interface is configured without System 800 identification, a special command must
be assigned to it before data exchange. After data exchange, it is enabled once more by
another command. When a serial interfrace is assigned the addressing data are transferred to
the SINUMERIK driver, which stores them in an internal list. In the event of data exchange the
SINUMERIK driver examines the status of the interface (assigned/unassigned) and the
message frame length and stores the message frame data in dual port RAM. Identification
bytes 6 to 10 are used for transmitting the command, message frame and error information
between the CP 315 and the user interfaces. In this way the structure of dual port RAM can
remain intact. Above this layer there is no difference in addressing between serial connection
and bus connection.The COM forwards the message frame on the basis of the addressing
data in the dual port RAM, in this case to the PLC or to the multiport RAM.
The addressed PLC recognizes that a message frame has been stored for it in the multiport
RAM. It transmits the data necessary for the user to the user interface addressed and stores
the useful data in the specified useful data block. The following data is transmitted to the user
interface:
•
Function number, characters 6 to 10 of the identification,
•
Useful data DB no. and
•
Data word no.
The function number is not used for message frames without System 800 identification with a
serial interface and therefore has a default value of 0.
6–14
© Siemens AG 1989 All Rights Reserved
06.91
6FC5 197-0AB20-0BP0
SINUMERIK 840/880 (PJ)
Advertisement
Table of Contents
