Siemens SIMATIC ET 200SP Manual page 177

CTT
Combined Transaction Type. Special AS-i slave profile:
CTT slaves require several AS-i cycles or several AS-i addresses for updating process data
between an AS-I slave and AS-i master.
The following CTT variants are defined:
CTT1: Slave profiles S-7.3, S-7.4
For cyclic data transmission of analog values or transparent data (up to 16 bits per channel).
Depending on the slave, the data transmission is in the direction of the input or output.
The S-7.1 and S-7.2 profiles are outdated profiles that are not managed automatically by the
AS-i master (function blocks are required for decoding the process data).
CTT2: Slave profiles S-7.5.5, S-7.A.5, S-B.A.5
For transmission of data blocks similar to data record transmission in
PROFIBUS/PROFINET.
The transmission can be initiated individually via the user program (acyclically, see "CTT2-
Request_lesen_schreiben (Read_Write_CTT2_String)") or automatically by the master
(cyclically, same as for analog values). Refer to the slave documentation.
The transmission process is managed automatically by the master and corresponds to a
serial data transmission with approximately 12 bytes (or 6 bytes for A/B address with
maximum configuration).
Depending on the slave, in parallel to the data block transmission, digital data of up to
2 DI / DO are also transmitted per AS-i cycle (5 ms or 10 ms for A/B address with maximum
configuration).
CTT3: Slave profiles S-7.A.7, S-7.A.A
For cyclic transmission of digital data.
Slave profile S-7.A.7 transmits 4 DI / 4 DO using a slave with A/B address. Like for standard
slaves, the inputs are transmitted in each AS-i cycle (5 ms or 10 ms for A/B address with
maximum configuration). The outputs require double the transmission time.
Slave profile S-7.A.A transmits 8 DI / 8 DO using a slave with A/B address. The inputs and
outputs are transmitted using four AS-i cycles.
CTT4: Slave profiles S-7.A.8, S-7.A.9
For cyclic transmission of analog values or transparent data (up to 16 bits per channel) in the
input direction using a slave with A/B address.
Depending on the slave, in parallel to the data block transmission, digital data of up to 1 DO
can also be transmitted per AS-i cycle (5 ms or 10 ms for A/B address with maximum
configuration).
CTT5: Slave profile S-6.0.x, where x = 2 ... 7, A ... C
For cyclic transmission of analog values or transparent data (up to 16 bits) in the input and
output direction.
The CTT5 types each occupy 2, 3, or 4 slave addresses simultaneously, depending on the
data record, so that consistent transmission of the full data width occurs in each AS-i cycle
(5 ms).
AS-Interface master CM AS-i Master ST (3RK7137-6SA00-0BC1)
Manual, 07/2017, A5E02655262020A/RS-AD/004
Glossary
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