Siemens CP 243-2 User Manual
Access to the Data of the AS-i Slaves
3-2
SIMATIC NET CP 243-2 AS-i Master
C79000-G8976-C142/02
3.1
Access to the Binary Data of the AS-i Slaves
3.1.1
Addressing the AS-i Slaves in the User Program
Requirements
Before you can access the I/O data of the AS-i slaves, the following requirements
must be met:
must be met:
Deactivate the filtering of the analog inputs for the CP 243–2 in the system data
block of the S7–200 CPU.
block of the S7–200 CPU.
Set the “PLC_RUN” bit (bit 7) in the digital control byte to ’1’ at the beginning of
the cyclic program.
the cyclic program.
Access to the I/O data of the slaves is then only allowed when the “CP_Ready”
bit (bit 1) in the digital status byte is set to ’1’.
bit (bit 1) in the digital status byte is set to ’1’.
Access to the Binary Values
The CP 243-2 assigns four bits (a nibble) in the input and output data area for
each AS-i slave. The PLC can write (slave output data) and read (slave input data)
this nibble.
each AS-i slave. The PLC can write (slave output data) and read (slave input data)
this nibble.
This allows bi-directional slaves to be addressed.