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
64
Manual, 04/2011, A5E00369892-03
Protocol parameters
You can only set the protocol parameters if you have not set the default values in the
protocol.
Table 2- 3 Protocol parameters (3964(R) procedure)
Parameter Description Range of values Default value
Character delay time The character delay time defines the
maximum permissible time which may
elapse between two received characters in
a message frame.
10 ms to 65530 ms in
10 ms increments
20 ms
Acknowledgment delay time The acknowledgment delay time defines
the maximum permissible time which may
elapse before the partner's
acknowledgment arrives during connection
establishment (time between STX and
partner's DLE acknowledgment) or
termination (time between DLE ETX and
partner's DLE acknowledgment).
10 ms to 65530 ms in
10 ms increments
2000 ms
(550 ms for 3964
without block check)
Connection attempts This parameter defines the maximum
number of attempts the CP 340 is allowed
in order to establish a connection.
1 to 255 6
Transmission attempts The parameter defines the maximum
number of attempts to transfer a message
frame (including the first one) in the event
of errors.
1 to 255 6
Baud rate/Character frame
The table below describes the baud rate/character frame.
Table 2- 4 Baud rate/Character frame (3964(R) procedure)
Parameter Description Range of values Default value
Baud rate Data transmission rate in bps
 2400

4800
 9600

19200
 9600
Start bit During transmission, a start bit is prefixed to
each character to be sent.
 1 (fixed value)  1
Data bits Number of bits onto which a character is
mapped.

7
 8

8
Stop bits During transmission, stop bits are appended to
every character to be sent, indicating the end of
the character.

1
 2

1