Appendix; Acyclic Data Transfer Via Ctt2 - Siemens SIRIUS M200D Manual

Appendix

A.1

Acyclic data transfer via CTT2

As well as transferring the extended process image cyclically by means of CTT2 (Combined
Transaction Type 2 (Page 123)), Slave 1 also transfers data set information to the motor
starter, or receives it from the motor starter, acyclically.
The process of transferring CTT2 data from the CPU to AS-i master is dependent on the
master.
The section that follows describes the process using the example of the DP/AS-i Link
Advanced.
For more details, please refer to the manual for the DP/AS-i Link Advanced.
If you are not using a SIEMENS AS-i master, please observe the information in the
documentation for the master you are using. The way in which the data transfer process is
structured differs according to the SIEMENS AS-i master in question.
If you are working with SIEMENS AS-i masters and SIMATIC S7 controllers, FC ASI_3422
offers a user-friendly command interface.
Please note, however, that FC ASI_3422 does NOT work with third-party AS-i masters.
Calling block FC ASI_3422 enables you to both transfer commands and accept response
data. For this purpose, FC ASI_3422 administers the calls Write_data_set and
Read_data_set autonomously.
When the command interface is called using command 44
the send buffer (Page 161)), a byte string can be used to send a CTT2 request to the AS-i
master. This forwards the string bytes to the AS-i slave address specified in the send buffer
(byte 1; see the table titled "Job data in the send buffer").
The AS-i master determines the number of string bytes to be sent to the AS-i slave (and,
therefore, to the motor starter M200D; the number depends on the data set to be transferred)
on the basis of byte 2 of the send buffer (number of string bytes).
The addressed AS-i slave responds to the CTT2 request with a CTT2 response. The AS-i
master communicates this response as a byte string in the receive buffer.
The structure of the CTT2 request or CTT2 response (code, index, etc.) begins with string
byte 1 in each case and is not dependent on the master. Details of this are outlined below.
M200D AS-Interface Standard
Manual, 08/2014, A5E02548958A/RS-AA/004
(byte 0; see the table Job data in
H
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