Valid Control Signals Of The Rs-232-C (V.24) Interface In Handshake On Mode - Siemens SIMATIC S5 CP 523 Manual

Technical Description
RS-232-C (V.24) interface with handshake ON
The RS-232-C (V.24) interface of the CP 523 can handle the following signals in handshake ON
mode:
Table 2-2. Valid Control Signals of the RS-232-C (V.24) Interface in Handshake ON Mode
Control signal
Outputs
TXD
DTR
ON
OFF
RTS
ON
OFF
Inputs
RXD
DSR
ON
OFF
CTS
ON
OFF
Note:
An XON/XOFF protocol is not possible if you evaluate the control signals (handshake ON).
In 3964(R) mode, handshaking is not possible (hardware signals are neither evaluated nor
affected).
2-8
State
Send data
CP holds send line at logic 1 when not transmitting
(V -3 V).
Data Terminal Ready
CP 523 switched on; ready to receive
CP 523 not switched on; not ready to receive
Request to send
CP 523 ready to send
CP 523 not sending
Receive data
Receive line must be held at logic 1 by the peripheral
device (V -3 V).
Data set ready
Peripheral device switched on; ready to receive
Peripheral device not switched on; not ready to receive
Clear to send
Peripheral device can receive characters from the
CP 523
The CP expects this as reply to RTS = "ON"
Peripheral device cannot receive characters from the
CP 523
Meaning
EWA 4NEB 811 6044-02a
CP 523