BECKHOFF C1120 - Manual (Page 27)

C1120 S5 to II/O Lightbus Interface Beckhoff II/O-Lightbus System
Date 27.06.97 Version 2.1 Page 27 of 52
Parallel Communication Channel
The parallel channel is used to start service functions of the C1120 interface. The channel
occupies the addresses 250 to 253 by default. This setup can be changed to any address
between 128 and 255.
The following information structure is available (shown for PB/PY default):
PB/PY 253 = parallel channel handshake
PB/PY 252 = parallel channel function number
PB/PY 251 = parallel channel argument 1
PB/PY 250 = parallel channel argument 2
The handshake is carried out with the peripherial address PB/PY 253 or equivalent. Following
control bits represent status information to both sides ( S5 --> C1120 and C1120 --> S5 ):
Bit 253.7: strobebit for parallel handshake
Bit 253.6: acknowlege bit for parallel handshake
The PLC is always the master of the communication via the parallel channel: the function call
is handed to the C1120 interface. The C1120 responds with data belonging to the function
call.