Data Transfer Using The Ascii Driver; Rs 232C Accompanying Signals - Siemens SIMATIC CP 340 User Manual

Basic Principles of Serial Data Transmission

2.5 Data transfer using the ASCII driver

2.5 Data transfer using the ASCII driver
Introduction
The ASCII driver controls data transmission via a point-to-point connection between the
CP 340 and a communication partner. This driver contains the physical layer (layer 1).
The structure of the message frames is left open through the S7 user passing on the
complete send message frame to the CP 340. For the receive direction, the end criterion of a
message must be parameterized. The structure of the send message frames may differ from
that of the receive message frames.
The ASCII driver allows data of any structure (all printable ASCII characters as well as all
other characters from 00 through FFH (with 8 data bit character frames) or from 00 through
7FH (with 7 data bit character frames)) to be sent and received.
2.5.1

RS 232C accompanying signals

RS 232C accompanying signals
The following RS 232C accompanying signals are available on the CP 340-RS 232C:
● DCD (input) Data carrier detect;
● DTR (output) Data terminal ready;
● DSR (input) Data set ready;
● RTS (output) Request to send;
● CTS (input) Clear to send;
● RI (input) Ring Indicator;
When the CP 340-RS 232C is switched on, the output signals are in the OFF state (inactive).
You can parameterize the use of the DTR/DSR and RTS/CTS control signals by means of
the CP 340: Point-to-Point Communication, Parameter Assignment user interface or control
them via functions (FCs) in the user program.
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Data carrier detected
CP 34x ready for operation
Communication partner ready for operation
CP 34x ready to send
Communication partner can receive data from CP 34x
(Response to RTS = ON of the CP 34x)
Ring Indicator
PtP coupling and configuration of CP 340
Manual, 04/2011, A5E00369892-03