Siemens SIRIUS 3RK3 - Structure of the Transfer Protocol

7.6.6 Structure of the transfer protocol
CTT2 codes and feedback messages (request/response)
The CTT2 slave supports the following CTT2 codes and feedback messages for transferring data
sets:
Code Meaning according to AS‑i spec.
V3.0
Followed by
144
dec
(90
H
) Read response not OK Standard error code
29
dec
(1D
H
) Exchange request index, read length, write length, write data
93
dec
(5D
H
) Exchange request OK read data
157
dec
(9D
H
) Exchange request not OK Standard error code, data set error code
index: Data set number; for MSS 3RK3 always 3
read length: expected returned data; C8
H
write length: length of the data to be written 0E
H
write data: data to be transmitted, see Chapter "Diagnostics using the CTT2 protocol
(Page 310)"
This CTT2 data structure is de󹪝ned in the AS-i speci󹪝cation V3.0 and therefore has the same
structure for all AS-i masters. The various manufacturers of AS-i masters use di󹪜erent
mechanisms for transferring this CTT2 data to the master, however (command interface or
comparable methods). Please refer to the user documentation for the AS-i master for detailed
information on this.
The complete transmission protocol consists of the master-speci󹪝c component of the protocol
and the non-master-speci󹪝c CTT2 data.
Acyclic CTT2 data transmission (code 29
dec
(1D
H
))
The acyclic CTT2 data transmission makes precise diagnostics of the individual elements
possible. If an event is signaled through the cyclic diagnostics data, the cyclic CTT2 data
transmission can be interrupted. The AS‑i Master can read all messages of the elements with
errors or a prewarning. The command is entered in DS3 to distinguish which error type is
pending. You will 󹪝nd additional information in Chapter " Reading / writing data set 3
(Page 310)."
CTT2 code Data set Command Byte
exchange 29
dec
DS3 - command interface "element
accesses"
Elements with errors: Read messag‐
es
52
H
Elements with prewarnings: Read
messages
72
H
Diagnostics / service
7.6 Diagnosis using AS-Interface (CTT2 protocol)
SIRIUS 3RK3 Modular Safety System
308 Equipment Manual, 07/2020, NEB926253002000/RS-AC/006