No. 44: Read_Write_Ctt2_String - Siemens SIMATIC ET 200SP Manual

Using the command interface
9.4 Description of the AS-i commands
Byte
Bit 7
19
20
21
22
23
24
25
26
27
28
29
30
31
9.4.21

No. 44: Read_Write_CTT2_String

Meaning
This command sends a CTT2 request according to the AS-i slave profile
"CombinedTransactionType2" to the AS-i master with a byte string. The master forwards the
string bytes to the AS-i slave address specified in the send buffer.
This command transfers a send buffer with up to 222 bytes to the AS-i master. The
AS-i master calculates the actual number of string bytes to be sent to the AS-i slave from
byte 2 of the send buffer.
The addressed AS-i slave answers the CTT2 request with a CTT2 response. The AS-
i master communicates this response as a byte string in the receive buffer. The strings are
transmitted by the AS-i master with the response.
The structure of the CTT2 request or CTT2 response (code, index, etc.) starts with string
byte 1 in each case. You will find details about this in the respective AS-i slave description.
Note
While transmission of the strings is being executed on AS-i, there is no cyclic data transfer
with the addressed AS-i slave. The type of protocol used means that transfer of up
to 200 bytes can take up to half a minute.
142
Bit 6 Bit 5
Par.Echo Slave 6B
Par.Echo Slave 8B
Par.Echo Slave 10B
Par.Echo Slave 12B
Par.Echo Slave 14B
Par.Echo Slave 16B
Par.Echo Slave 18B
Par.Echo Slave 20B
Par.Echo Slave 22B
Par.Echo Slave 24B
Par.Echo Slave 26B
Par.Echo Slave 28B
Par.Echo Slave 30B
Meaning
Bit 4 Bit 3
AS-Interface master CM AS-i Master ST (3RK7137-6SA00-0BC1)
Manual, 07/2017, A5E02655262020A/RS-AD/004
Bit 2 Bit 1
Par.Echo Slave 7B
Par.Echo Slave 9B
Par.Echo Slave 11B
Par.Echo Slave 13B
Par.Echo Slave 15B
Par.Echo Slave 17B
Par.Echo Slave 19B
Par.Echo Slave 21B
Par.Echo Slave 23B
Par.Echo Slave 25B
Par.Echo Slave 27B
Par.Echo Slave 29B
Par.Echo Slave 31B
Bit 0