Siemens SIMATIC CP 340 - Page 25

Basic Principles of Serial Data Transmission
2.1 Serial Transmission of a Character
PtP coupling and configuration of CP 340
Manual, 04/2011, A5E00369892-03
25
Character frame
Data is transmitted between the CP 340 and a communication partner via the serial interface
in a 10-bit or 11-bit character frame. Three data formats are available for each character
frame. You can assign parameters to the format you require using the CP 340: Point-to-Point
Communication, Parameter Assignment parameterization interface.
10-Bit Character Frame
The figure below shows the three possible data formats for an 10-bit character frame.
6LJQDOVWDWXV
6LJQDOVWDWXV
6LJQDOVWDWXV
VWDUWELW
GDWDELWV
VWRSELWV
VWDUWELW
GDWDELWV
SDULW\ELW
VWRSELWVWRSELW
VWDUWELW
GDWDELWV
GDWDELWVVWDUWELWGDWDELWVVWRSELW
6LJQDOVWDWXV
GDWDELWVVWDUWELWGDWDELWVSDULW\ELWVWRSELW
6LJQDOVWDWXV
GDWDELWVVWDUWELWGDWDELWVVWRSELW
6LJQDOVWDWXV
12 8910
12 8910
12 910
Figure 2-1 10-Bit Character Frame