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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:

 Deactivate the filtering of the analog inputs for the CP 243–2 in the system data

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.

 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’.

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.

This allows bi-directional slaves to be addressed.

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Siemens SIMATIC NET Manual de servicio Pagina 50