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Command Interface

5-57

SIMATIC NET CP 243-2 AS-i Master

C79000-G8976-C142/02

5.2.31 Read_AS-i_Slave_Diagnostic_String

Purpose

With this call, an diagnostic string complying with the AS-i slave profile 7.4 can be

read from the AS-i slave with the AS-i slave address specified in the send buffer.

The AS-i master supplies up to 223 bytes of reply data. The number of diagnostic

bytes actually sent by the AS-i slave is signaled by the AS-i master in byte 2 of the

receive buffer (number of diagnostic bytes).

If the AS-i slave sends a string longer than 220 bytes, the AS-i master aborts the

string transfer and terminates the job with an error. The received data are then not

made available to the user program.

As long as the string transfer is active, there is no user/analog data exchange with

the addressed AS-i slave.

Structure of the Job Data in the Send Buffer

Bank Byte Meaning

2 0 Command number 43

2 1 Slave address

Structure of the Job Data in the Receive Buffer

Bank Byte Meaning

2 0 Echo of the command number 43

2 1 Command status

2 2 Number of diagnostic bytes

2 3 String byte (1)

2 4 String byte (2)

... ... .....

... ... String byte (n–1)

... ... String byte (n)

Maximum value for n=220

1 2 ... 120 121 122 123 124 125 126 127 128 129 130 ... 149 150

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Siemens SIMATIC NET Manual de servicio Pagina 125