Siemens SIMATIC NET IE/AS-INTERFACE LINK PN IO, Руководство пользователя

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8 Using the Data Record Interface
162
IE/AS − INTERFACE LINK PN IO
as of hardware version 1, as of firmware version V2.0
Release 08/2018
C79000 − G8976 − C216 − 03
8.2.2.11 Read_Identification_String
Meaning
With AS-i slaves with profile 7.4, this call can be used to read an identification
string from the AS-i slave with the specified AS-i slave address. The AS-i master
returns up to 220 bytes of response data. The number of ID bytes actually sent by
the AS-i slave is signaled by the AS-i master in byte 2 (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
As an exception, with this call, the bytes contained in the bits “Follows” and “Valid”
are also transferred (see AS-i slave profiles of the combined transaction types).
Structure of the RecordDataRead service − Index 30
Byte Meaning
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 Version_hi = 0x00
1 Version_lo = 0x00
2
Number of string bytes
3 String byte 1
4 String byte 2
... ...
221 String byte 219 (may be irrelevant)
222 String byte 220 (may be irrelevant)