Read_Ctt2_String - Siemens SIMATIC NET IE/AS-INTERFACE LINK PN IO Manual

8 Using the Data Record Interface
8.2.2.13

Read_CTT2_String

Meaning
Using this call, an acyclic CTT2 request according to AS-i slave profile
"CombinedTranslationType2" can be read from an AS-i slave.
The request written with call "Index 001F" is responded to by the slave. The
response can be read with this call. In the response, the AS-i master transfers a
maximum of 223 bytes, a maximum of 220 of those can be string bytes. The actual
number of string bytes is contained in byte 2.
Only the last CTT2 response is read back. If several "Write_CTT2 string" jobs are
sent in succession, older responses are lost.
The structure of the CTT2 request or CTT2 response (code, index, ...) always
begins with string byte 1. For more detailed information, refer to the relevant AS-i
slave description.
As long as strings are being transferred on AS-i, there is no cyclic analog data
transfer with the addressed AS-i slave. Due to the type of protocol, the transfer of
approximately 200 bytes can take up to half a minute.
Structure of the RecordDataRead service − Index 31
Byte
Bit 7
0
1
2
3
4
...
221
222
IE/AS−INTERFACE LINK PN IO
164
Bit 6 Bit 5 Bit 4
Version_hi = 0x00
Version_lo = 0x00
Number of string bytes
String byte 219 (may be irrelevant)
String byte 220 (may be irrelevant)
as of hardware version 1, as of firmware version V2.0
Meaning
Bit 3 Bit 2
String byte 1
String byte 2
...
Bit 1 Bit 0
Release 08/2018
C79000−G8976−C216−03