Siemens CP 243-2 installation instructions ReadAS-iSlaveIDString

Command Interface

5.2.30Read_AS-i_Slave_ID_String

Purpose

With this call, an identification 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 always supplies 223 bytes of reply data. The actual number of ID bytes sent by the AS-i slave is signaled by the AS-i master in byte 2 of the receive buffer (number of ID 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.

Note

In contrast to other jobs, in this job, the bytes containing the bits ºFollowº and ºValidº are also transferred (see slave profile 7.4).

Structure of the Job Data in the Send Buffer

Bank Byte

20

21

Meaning

Command number 42 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 42 H

Command status

Number of ID bytes

String byte (1)

String byte (2)

.....

String byte (n±1)

String byte (n)

Maximum value for n=220

5-56	SIMATIC NET CP 243-2 AS-i Master
	C79000-G8976-C142/02