Siemens SIMATIC CP 340 User Manual page 69

Data flow control
The table below contains a description of the parameters for data flow control.
Data flow control is not possible with the RS 485 interface. Flow control with "RTS/CTS" and
"automatic control of V24 signals" is only supported on RS 232C interfaces.
Table 2- 8 Data flow control (ASCII driver)
Parameter
Data flow control
XON character
(1)
XOFF character
(1)
Waiting for XON after XOFF
(wait time for CTS = ON)
Time to RTS off
(Only with automatic control
of RS 232C accompanying
signals)
Data output waiting time
(Only with automatic control
of RS 232C accompanying
signals)
Only for data flow control with XON/XOFF.
(1)
Depending on whether you set 7 or 8 data bits for the character frame.
(2)
Only for data flow control with XON/XOFF or RTS/CTS.
(3)
For additional information, see RS 232C accompanying signals (Page 46).
PtP coupling and configuration of CP 340
Manual, 04/2011, A5E00369892-03
Description
Defines which data flow
control procedure is used.
Code for XON character
Code for XOFF character
Period of time for which the
CP 340 should wait for the
(3)
XON code or for CTS="ON"
of the communication partner
when sending.
Time to wait following
transfer before the CP 340
sets the RTS line to OFF.
The time the CP 340 waits
after setting the RTS line to
ON for CTS = "ON" from the
communication partner
before it initiates the transfer.
Basic Principles of Serial Data Transmission
Range of values
None

XON/XOFF

RTS/CTS

Automat. control of V24

signals
7 data bits:

0 to 7FH (hex)
(2)
8 data bits:

0 to FFH (hex)
(2)
7 data bits:

0 to 7FH (hex)
(2)
8 data bits:

0 to FFH (hex)
(2)
20 ms to 65530 ms
in 10 ms increments
0 ms to 65530 ms
in 10 ms increments
0 ms to 65530 ms
in 10 ms increments
2.7 Parameterization Data
Default value
None
(DC3)
(DC3)
20 ms
0 ms
0 ms
69