I/O modules • 247
TTY interface 750-651
Modular I/O System
ETHERNET TCP/IP
Attention
The data transmission takes place at 9600 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 TTY Interface is passive in sending and receiving, thus having no current
sources. For data conversion, an active partner is needed or an additional cur-
rent source has to be connected.
TxD
+
TxD
-
RxD
+
RxD
-
:$*2
Receiver
Transmitter
20 mA
Receiver
with current source
Transmitter with
current source
20 mA
TxD
+
TxD
-
RxD
+
RxD
-
:$*2
20 mA
Current source
20 mA
Current source
Receiver
Transmitter
TxD
+
TxD
-
RxD
+
RxD
-
:$*2
20 mA
Current source
Point to point connection
with active subscribers
Point to point connection with passive
subscriber and additional current sources
Bus connection with a current source
and a passive subscriber
Organization of the input and output data:
The module is a combination of an analog input and output module with 2 x
16 bit input and output data. The transfer of the data to be transmitted and the
received 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.
The control byte consists of the following bits:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
OL 2
OL1
OL0
0
IR
RA
TR
Constant
value
should
always be
0.
Frames available in output area
OL2 is always 0,
i.e. OL2, OL1, OL0 = 0,1,1
3 characters should be sent and
put into the output.
Constant
value
should
always be
0.
Initialization
request
Receive
acknow-
ledge
Transmit
request