Configuration - Siemens SINUMERIK 840C Installation Instructions Manual

10.94
12.28.3

Configuration

In order to avoid complicated programming involving pointers and lengthy run times in the PLC
user program, the configuring channel and data transfer areas are stored in different data
blocks: A "Configuring DB" with 32 DW (DB2) and "High-speed data channels" with 256 (DB
3) are set up in the link RAM; these blocks act as the communications link between the NC
and PLC.
Configuring channel in DB 2
Block of 11 DW in DB 2 by means of which one data transfer area in each case can be set in
DB 3 (unambiguous definition of data to be transferred). Regardless of how many transfer
areas are present in DB 3, there is only on configuring channel in DB2; several data transfer
areas must be configured one after another.
Contents of DB 3:
• Data transfer areas
A data transfer area is an element of the interface DB 3 which allows certain data to be
exchanged between the NC and PLC. The type and meaning of the data are defined in the
configuration.
• High-speed data channels
A high-speed channel is a certain type of data transfer area; its format and processing
mode can be specified. The length of a high-speed data channel is dependent on the type
of data to be transferred. These channels are accessed directly by the PLC user program,
thus allowing the cycle time (e.g. access to an alarm OB) of the updating function to be
controlled by the user. The maximum data exchange rate between the NC and this
interface corresponds to the interpolation cycle.
• Function identifier
Designation for a certain type of data transmission. The "High-speed data channels" are
defined here.
© Siemens AG 1992 All Rights Reserved
SINUMERIK 840C (IA)
6FC5197- AA50
12 Functional Descriptions
12.28.3 Configuration
12–283