No. 41: Read_String - Siemens SIMATIC ET 200SP Manual

9.4.30

No. 41: Read_String

Meaning
This command causes the AS-i slave to read a parameter string in accordance with AS-
i slave profile 7.4 with the AS-i slave address specified in the send buffer.
The AS-i master supplies up to 221 bytes of response data. The AS-i master signals the
actual number of parameter bytes sent by the AS-i slave in Byte 0 of the receive buffer.
If the AS-i slave sends a parameter string longer than 220 bytes, the AS-i master aborts
string transfer and terminates the job with an error. The received data is not made available
to the job program.
While transmission of the parameter string is being executed, there is no transfer of user
data / analog data with the addressed AS-i slave.
Structure of the job data in the send buffer
Table 9- 57 Structure of the job data in the send buffer
Byte
0
1
Structure of the response data in the receive buffer
Table 9- 58 Structure of the response data in the receive buffer
Byte
0
1
2
...
n - 1
n
Maximum value for n = 220
AS-Interface master CM AS-i Master ST (3RK7137-6SA00-0BC1)
Manual, 07/2017, A5E02655262020A/RS-AD/004
Meaning
Command number: 41
H
Slave address
Meaning
Number of parameter bytes
Parameter string byte 1
Parameter string byte 2
...
Parameter string byte n - 1
Parameter string byte n
Using the command interface
9.4 Description of the AS-i commands
149