BECKHOFF C1220 - Manual (Page 17)

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17 Software description of functions
Beckhoff Lightbus - PC interface card C1220
Example of a descriptor:
Telegram to I/O module 1 : D0 - D2 Outputs
D3 Input
The data for the output in D0 - D2 is fetched from the addresses 0x400,
0x302 and 0x210 in the DPRAM.
The data item for the input in D3 is stored at the address 0x30 in the
DPRAM.
Bytes Contents
0,1 0x01, 0x00
2,3 0x10, 0x00
4,5 0x00, 0x04
6,7 0x02, 0x03
8,9 0x10, 0x02
10,11 0xff, 0xff
12,13 0xff, 0xff
14,15 0xff, 0xff
16,17 0xff, 0xff
18,19 0x30, 0x00
Constants At the DPRAM adress offset 0xEF0 - 0xFEF the constants 0x00 - 0xFF can
be found. To insert constants into the data bytes of the Lightbus telegrams,
you just have to set the descriptor to the corresponding offset.
The above-mentioned CDLs are split into parts so they can be transferred
via the handshake channel 0. In doing so, the information for a message
must not be split. Transfer can be activated with the function 0x10.
Argument Channel Length Function blank
0 1 2 ... n
Request nn 0x10 00 aa bb db1,0 dbn,19
Argument Channel Length Function
0 1 2
Comment
Reply 04 0x10 aa 00 o.k.
04 0x10 aa 01 Error in CDL data
(e.g.: Pointer not in the DPRAM’s data area)
04 0x10 aa 02 CDL overflow
04 0x10 aa 03 Invalid descriptor length