Line Connection; Functional Description; Block Diagram - Westermo MD-45 AC Manuel D'installation

7.0 Functional description

When the converter is set to data-control mode the transmitter is activated by data on
TD (RS-232). The time the transmitter stays active corresponds to one character-time
and turning time for the set data rate and number of bits. If there is more data on TD
before the turning time is ended the transmitter stays active for additional one character.
In RTS-control mode the transmitter is activated by the RTS-signal. In this mode the
switches for data rate and number of bits has no effect. The LED indicators is controlled
by the data signals. The active termination secures that the signal level at the receiver is
in off-state (>0.2 Volts) when there is no data transmission. Full duplex is only possible if
RS-422 is used.

7.1 Block diagram

V.24/RS-232
3
TD
7
RTS
8
CTS
6
DSR
2
RD
5
0V
SG
A
Power
F1
supply
6157-2003
TD LED TD LED
RTS LED
CTS
LED
MCU
+5V
RD
LED
S1:6
+5V
A
0V
A
Insulated power supply
S2:4
+5V
B
Bus termination
0V
B
+5V
B
Bus termination
S2:2
0V
B
0V
+5V
B
0V
B
V.11/RS-422
RS-485
3
A
4
B
S2:3
S2:1
1
A'
2
B'
5
Shield
B
27