Product overview
2.4 Properties of the RS232 interface
CM PtP RS232 HF (6ES7541‑1AD00‑0AB0) communication module
14
Manual, 01/2013, A5E03790665-01
2.4
Properties of the RS232 interface
Definition
The RS232 interface is a voltage interface used for serial data transmission.
Properties
The RS232 interface has the following properties and meets the following requirements:
Type
Voltage interface
Front connector
9-pin sub-D male connector with screw lock
RS232 signals
TXD, RXD, RTS, CTS, DTR, DSR, RI, DCD, GND; all signals isolated
against the backplane bus and load voltage
Max. data transmission
rate
115.2 kbps
max. cable length
15 m, cable type LIYCY 9 x 0.14
Standard
DIN 66020, DIN 66259, EIA-RS 232C, CCITT V.24/V.28
RS232 signals
The table below shows the meaning of the individual RS232 accompanying signals.
Table 2- 2
Signals of the RS232 interface
Signal
Designation
Meaning
TXD
Transmit Data
Transmit data; transmit cable logically held to "1" by communication module in idle
state.
RXD
Receive Data
Receive data; receive cable logically held to "1" by communication partner in idle state.
RTS
Request To Send
Request to send
RTS set to "ON": Communication module ready to send; signals to the communication
partner that there is data ready to send
RTS set to "OFF": Communication module not ready to send
CTS
Clear To Send
Clear to send
CTS set to "ON": Signals "clear to send" to the communication partner
CTS set to "OFF": Signals "Not clear to send" to the communication partner
DTR
Data Terminal Ready DTR set to "ON": Communications module switched on, ready for operation
DTR set to "OFF": Communications module not switched on, not ready for operation
DSR
Data Set Ready
DSR set to "ON": Communication partner signals "ready for operation"
DSR set to "OFF": Communication partner not switched on, not ready for operation
RI
Ring Indicator
Incoming call when connecting a modem
DCD
Data Carrier Detect
Carrier signal when connecting a modem. The communication partner signals with a
high level that it detects incoming data on the cable.
