BECKHOFF C1220 - Manual (Page 16)

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Software description of functions 16
Beckhoff Lightbus - PC interface card C1220
Configuration
A total of four functions is available for description of the configuration, of
affiliation of the inputs or outputs in the Beckhoff Lightbus to the addresses
in the DPRAM, and the affiliations of the modules to the processor groups.
The configuration is also transwhereted via the handshake channels.
The management part of the communication functions must be reinitialized
at the start of a new configuration.
Each of the maximum number of 8 communication functions can be
optionally configured as CDL communication or as freely programmable
communication.
A further function configures the interrupt channels for the address-
independent interrupts.
Reinitializing communication management
Both the CDLs and also the freely programmable communication functions
consist of two parts, a data part and a management part. The management
parts must be reset before new configurations are communicated. The
management parts of all 8 communication functions are reset by activating
the function 0ch.
Argument Channel Length Function
0 1 2
Comment
Request 02 0x0c
Reply 03 0x0c 00
CDL communication
A CDL is generated for each group of modules whose process image is to
updated jointly. This CDL is composed of so-called descriptors. A
descriptor describes a telegram for a module and is structured as follows:
Bytes Contents
0,1 II/O module address (1 - FE)
2,3 Control Word :
0x0000: READ
0x0010: READ/WRITE
0x0030: RAM
0x00B0: BROADCAST
4,5 Pointer to byte for output in D0 of a message
6,7 Pointer to byte for output in D1 of a message
8,9 Pointer to byte for output in D2 of a message
10,11 Pointer to byte for output in D3 of a message
12,13 Pointer to byte for input in D0 of a message
14,15 Pointer to byte for input in D1 of a message
16,17 Pointer to byte for input in D2 of a message
18,19 Pointer to byte for input in D3 of a message