Command Interface

5.2.31Read_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

20

21

Meaning

Command number 43 H

Slave address

Structure of the Job Data in the Receive Buffer

Bank

Byte

 

 

2

0

2

1

 

 

2

2

 

 

2

3

 

 

24

... ...

... ...

... ...

Meaning

Echo of the command number 43 H

Command status

Number of diagnostic bytes

String byte (1)

String byte (2)

.....

String byte (n±1)

String byte (n)

Maximum value for n=220

SIMATIC NET CP 243-2 AS-i Master

5-57

C79000-G8976-C142/02

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Siemens CP 243-2 installation instructions ReadAS-iSlaveDiagnosticString