Description of the communication channels – BECKHOFF C1220 User Manual
Page 9
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9
Software description of functions
Beckhoff Lightbus - PC interface card C1220
Description of the communication channels
Two channels are configured for communication between the PC bus and
C1220. Each channel embraces 255 bytes. The PC writes the data
required for requesting the required function into the channel 0 and then
outputs a DV (Data Valid). After acceptance of the data, the C1220 module
outputs the ‘Quit’ signal. The PC withdraws the ‘DV’ and a new
communication can be commenced as soon as the ‘Quit' signal is 0.
Channel 0 from the PC bus to the C1220 provides the address area from
0xC01 to 0xCFF for the data. DV is the MSB of the address 0xC00. 'Quit' is
the second highest bit of the address 0xD00.
Communication channel 0:
Byte 0
0xC00
Byte 1
................
Byte 254
Byte 255
0xCFF
Channel 1 from the C1220 module to the PC bus provides the address
area from 0xD01 to 0xDFF for the data. DV is the MSB of the address
0xD00. 'Quit' is the second highest bit of the address 0xC00.
Communication channel 1:
Byte 0
0xD00
Byte 1
................
Byte 254
Byte 255
0xDFF
Addresses of the
Address
Address bits
Contents
Komunikationskanäle
7
6
5
4
3
2
1
0
0xC00
1
0
0
0
0
0
0
0
’Data Valid’ for
Channel 0
(in the case of PC -> C1220 data
transfer)
0xC00
0
1
0
0
0
0
0
0
’Quit’ for Channel 1
(in the case of C1220 -> PC data
transfer)
0xC01
Length (von 2 bis 0xFE)
0xC02
Functionsnummer
(1 bis 0xFE)
0xC03
Argument 0
..
..
0xCnn
Argument n
..
..
0xCFF
..
0xD00
1
x
0
0
0
0
0
0
’Data Valid’ for
Channel 1
(in the case of C1220 -> PC data
transfer)
0xD00
x
1
0
0
0
0
0
0
’Quit’ for Channel 0
(in the case of PC -> C1220 data
transfer)
0xD01
Length (from 2 to 0xFE)