Contrel EMA11, User Manual, Page: 27 / 58

EMA11 - USER MANUAL
-27-
8.4.2) RS485 CONNECTION SHIELDED
Although the signal is given by the difference between A and B voltage, a ground connection is
needed to eliminate or to reduce the common mode noise induced (into the bus).
To reduce the EMI interferences need to connect the shield directly to a ground at one end and with a
series RC network at the other end.
R = 100
Ω
C = 33µF.
The max length of the stubs is 20cm.
8.4.3) RS232 CONNECTION
If a RS232 communication line is shorter of 5 mt. and a multidrop network will not use, it’s not
necessary to use a serial line converter because the serial output is compatible with the PC., as shown
on the above mentioned picture.
A RS232 could reach 15mt. but the presence of noises in the industrial application could cause
breakdown in the communication.
The connection from EMA serial port RS232 to PC RS232 serial port is a PTP, Pin To Pin, connection.
SIGNAL EMA11 DB9 (PC)
TX 1 PIN 2
RX 2 PIN 3
GND 3 PIN 5
EMA 11 EMA 11
RS232/RS485
converter
COM
TX
TX
RX
Rt
Max 32 EMA; max 1200 mt
RX
COM
RS232
B
A
Rt
EMA 11
RS232
RX
TX
COM