Siemens SIMATIC CP 340, User Manual

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Basic Principles of Serial Data Transmission
2.7 Parameterization Data
PtP coupling and configuration of CP 340
Manual, 04/2011, A5E00369892-03
67
Protocol parameters
The table below describes the protocol parameters.
Table 2- 6 Protocol parameters (ASCII driver)
Parameter Description Range of values Default value
Indicator for end of received
message frame
Defines which criterion
signals the end of each
message frame.

After character delay time
expires
 On receipt of end-of-text
character(s)

On receipt of a fixed
number of characters
After character delay time
expires
Character delay time The character delay time
defines the maximum
permissible time interval
between 2 characters
received consecutively.
(1)
4 ms to 65,535 ms 4 ms
End-of-text character 1
(2)
First end code
 At 7 data bits:
0 to 7FH (Hex)
(3)

8 data bits:
0 to FFH (hex)
(3)
3
End-of-text character 2
(2)
Second end code, if
specified
 At 7 data bits:
0 to 7FH (Hex)
(3)

8 data bits:
0 to FFH (hex)
(3)
0
Message frame length when
received
(4)
When the end criterion is
"Fixed message frame
length", the number of bytes
making up a message frame
is defined.
1 to 1024 (bytes) 240
(1)
The minimum character delay time is the time required to transfer 4 characters.
(2)
Can only be set if the end criterion is an end-of-text character.
(3)
Depending on whether you set 7 or 8 data bits for the character frame.
(4)
Can only be set if the end criterion is fixed message frame length.