User Manual

Communication via AS-i - only for G110M
7.5 Cyclic and acyclic communication via CTT2
Fieldbuses
226 Function Manual, 04/2018, FW V4.7 SP10, A5E34229197B AE
7.5
Cyclic and acyclic communication via CTT2
Via CTT2 (Combined Transaction Type 2), both cyclical and acyclical communication is
performed via AS-i. Because only one channel is available (AS-i.DO1 master -> slave or AS-
i.DI3 slave -> master), a concurrent cyclical and acyclical data exchange is not possible.
The communication type (cyclical or acyclical) is always coded in the first byte in accordance
with the following table.
Table 7- 6 CTT2 commands
Code
(hex)
Explanation/meaning
Followed by
Cyclic communication
Access to analog values via DS140 … DS147. See CP 343−2
/ CP 343−2 P AS−Interface master
(http://support.automation.siemens.com/WW/view/en/558165
7), Chapter 4
4 bytes: PWE1, PWE2
4 bytes: PWE1, PWE2
Acyclic communication - standard
10 hex Read request: Master -> slave 2 bytes: Index, length
50 hex
Read request OK: Slave -> master
Index, data
90 hex
Read request failed: Slave -> master
1 byte: Standard error code (3 hex)
11 hex
Write request: Master -> slave
Index, length, data
51 hex
Write request OK: Slave -> master
91 hex
Write request failed: Slave -> master
1 byte: Standard error code (3 hex)
Acyclic communication - manufacturer-specific
12 hex
Read request: Master -> slave
Index, length
52 hex
Read request OK: Slave -> master
Data
92 hex
Read request failed: Slave -> master
Fault object
13 hex
Write request: Master -> slave
Index, length, data
53 hex
Write request OK: Slave -> master
93 hex
Write request failed: Slave -> master
Fault object
1D hex Exchange request: Master -> slave Index, read length, write length, write
data
5D hex
Exchange request OK: Slave -> master
PKE, index, n-2 data
9D hex Exchange request faulty: Slave -> master Fault object