Siemens S7-1200 - Page 691

Communication processor and Modbus TCP
12.3 Point-to-point (PtP) communication
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
691
Parameter and type
Data type
Description
SEQ[1].CTL IN Byte Sequence 1 ignore/compare control for each character: (Default
value: B#16#0)
These are the enabling bits for each character in start sequence
• 01H - Character 1
• 02H - Character 2
• 04H - Character 3
• 08H - Character 4
• 10H - Character 5
Disabling the bit associated with a character means any character
will match, in this sequence position.
SEQ[1].STR
IN
Char[5]
Sequence 1 start characters (5 characters). Default value: 0
SEQ[2].CTL IN Byte Sequence 2 ignore/compare control for each character. Default
value: B#16#0)
SEQ[2].STR
IN
Char[5]
Sequence 2 start characters (5 characters). Default value: 0
SEQ[3].CTL IN Byte Sequence 3 ignore/compare control for each character. Default
value: B#16#0
SEQ[3].STR
IN
Char[5]
Sequence 3 start characters (5 characters). Default value: 0
SEQ[4].CTL IN Byte Sequence 4 ignore/compare control for each character. Default
value: B#16#0
SEQ[4].STR
IN
Char[5]
Sequence 4 start characters (5 characters), Default value: 0
Example
Consider the following received hexadecimal coded message: "
68
10 aa
68
bb 10 aa 16"
and the configured start sequences shown in the table below. Start sequences begin to be
evaluated when the first 68H character is successfully received. Upon successfully receiving
the fourth character (the second 68H), then start condition 1 is satisfied. Once the start
conditions are satisfied, the evaluation of the end conditions begins.
The start sequence processing can be terminated due to various parity, framing, or inter-
character timing errors. These errors result in no received message, because the start
condition was not satisfied.
Table 12- 16 Start conditions
Start condition
First Character
First Character +1
First Character +2
First Character +3
First Character +4
1
68H
xx
xx
68H
xx
2
10H
aaH
xx
xx
xx
3 dcH aaH xx xx xx
4
e5H
xx
xx
xx
xx