Siemens S7-1200 System Manual page 679

With this configuration, the start condition is satisfied when either pattern occurs:
● When a five-character sequence is received where the first character is 0x6A and the fifth
● When two consecutive 0x6A characters are received, preceded by any character. In this
Example sequences that would satisfy this start condition are:
● <any character> 6A 6A
● 6A 12 14 18 1C
● 6A 44 A5 D2 1C
Message end conditions
You also configure how the communication interface recognizes the end of a message. You
can configure multiple message end conditions. If any one of the configured conditions
occurs, the message ends.
For example, you could specify an end condition with an end of message timeout of 300
milliseconds, an inter-character timeout of 40 bit times, and a maximum length of 50 bytes.
The message will end if the message takes longer than 300 milliseconds to receive, or if the
gap between any two characters exceeds 40 bit times, or if 50 bytes are received.
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
character is 0x1C. The characters at positions 2, 3, and 4 can be any character with this
configuration. After the fifth character is received, evaluation of end conditions begins.
case, evaluation of end conditions begins after the second 0x6A is received (3
characters). The character preceding the first 0x6A is included in the start condition.
Communication processor and Modbus TCP
12.3 Point-to-point (PtP) communication
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