I/O modules • 253
RS485C interface 750-653
Modular I/O System
ETHERNET TCP/IP
The 16 byte output buffer provides for faster transmission of larger data
strings.
Attention
The data transmission takes place at 9,600 baud (default value). 1 start bit, 8
data bits and 1 stop bit will be transmitted. No parity is available. The drivers
are high impedence. The control of data is made by the user software.
Attention
The interface module can be used for bus connections as well as for point to
point connections. With bus connections, modules that are not connected to
the power supply can also be wired. They do not disturb the bus connection.
:$*2
M
M
S
S
TxD
+
RxD
-
RxD
+
TxD
-
point to point connection
bus connection
transmitter and
receiver
receiver
transmitter
:$*2
M
M
S
S
TxD
+
RxD
-
RxD
+
TxD
-
transmitter nd
receiver
transmitter and
receiver
termination
termination
Organization of the input and output data:
The module is a combination of analog input and output module with 2 x 16
bit input and output data. The transfer of the data to be transmitted and the re-
ceived data is made via 3 output and 3 input bytes. One control byte and one
status byte are used to control the floating data.
Requests are indicated by a bit change of state. An assigned bit indicates exe-
cution by adopting the value of the request bit.
Up to 3 characters which have been received via interface can be stored in the
input bytes 0 to 2. The output bytes will contain the characters to be sent.