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06.91
4
COM
4.1
Structure
The outline structure of the COM area is shown in figure "COM structure". The task of the
COM area is to distribute data or to process data by means of routines. The interface between
interface module and COM area is the common dual port RAM. Using the local bus of the NC
control the COM area can either retrieve data from the dual port RAM or store data there. The
interface modules are passive, i.e. they do not access other memories via the local bus.
The interface between COM area and PLC is the multiport RAM. Data which is processed in
the PLC is stored by the COM area in the multiport RAM.
Three processes are executed in the COM area:
•
Store files in or retrieve them from the message frame memory
•
Pass data to the PLC
•
Process functions by means of standard routines.
The SINUMERIK 880 contains its own COM CPU.
The COM area in the SINUMERIK 840 is built into the NC CPU.
Standard routines
Connection
monitoring
Filetransfer
PP
memory
Interface module
bus
COM structure
© Siemens AG 1989 All Rights Reserved
SINUMERIK 840/880 (PJ)
PLC
Multiport RAM
Data distributor
of
computer link
Dual port RAM
Interface module
6FC5 197-0AB20-0BP0
COM
serial
4 COM
4.1 Structure
4–1
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