Moeller LE 4-505-BS1, Hardware And Engineering

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9 Operation
The ASi master LE 4-505-BS1 is closely linked to the
PLC both physically and functionally. The PLC carries
out overlying activities such as update of the process
image with the I/O data of the ASi slaves and control of
the operating mode of the ASi master.
Data between the PLC and ASi slaves is transferred
via a buffer in the ASi master. This allows a master/
slave communication which is independent of data
exchange between the ASi master and the PLC.
The ASi master polls the slaves sequentially in order
of increasing slave address. When each slave is
polled, output data is transferred from the buffer to
the slave and input signals contained in the slave
response are written to the buffer. At the end of each
user program cycle, the PLC exchanges the slave
data in the process image with the slave data in the
buffer of the ASi master.
Figure 15: Data transfer between the PLC and an ASi slave
PS 4-201-MM1 LE 4-505-BS1
Process
image
(ASi master)
Data buffer
ASi slave
Inputs
Outputs
LE bus
ASi two-core
flat cable
H1314G.BK Seite 51 Freitag, 2. Juli 1999 9:02 09