Siemens SIMATIC S7 System Manual page 243
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Parameter
Start Character
character
Start on Any Character The Any Character condition specifies any successfully received character
Line Break
Idle Line
Special condition:
Recognize message
start with single
Special condition:
Recognize message
start with a character
sequence
Sample configuration
S7-1200 Programmable controller
System Manual, 11/2009, A5E02486680-02
8.5 Configuring the transmit (send) and receive parameters
Definition
The Start Character condition specifies that successfully receiving a
particular character will begin a message. This character will be the first
character within a message. Any character that is received before this
specific character will be discarded.
will begin the start of a message. This character will be the first character
within a message.
The Line Break conditions specifies that a message receive operation
should start after a break character is received.
The Idle Line condition specifies that a message reception should start once
the receive line has been idle or quiet for the number of specified bit times.
Once this condition occurs, the start of a message will begin.
Specifies that a particular character indicates the start of a message. The
default is STX.
Specifies that a particular character sequence indicates the start of a
message. For each sequence, you can specify up to five characters. For
each character position, you specify either a specific hex character, or that
the character is ignored in sequence matching.
Incoming sequences will be evaluated against the configured start
conditions until a start condition has been satisfied. Once the start sequence
has been satisfied, evaluation of end conditions begins.
You can configure up to five specific character sequences, which you can
enable or disable as needed. The start condition is satisfied when any one
of the configured character sequences occurs.
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 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.
When two consecutive 0x6A characters are received, preceded by any
character. In this 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.
Example sequences that would satisfy this start condition:
<any character> 6A 6A
6A 12 14 18 1C
6A 44 A5 D2 1C
Point-to-Point (PtP) communications
243
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