Contrel EMA90 User Manual

EMA90 - USER MANUAL
-27-
8.4.2) RS485 CONNECTION NOT SHIELDED
Once a RS485 network has been configured; to communicate between the Host (computer) and the
instrument(s) (EMA) a serial interface converter must be wired between PC and instrument(s) as
mentioned on the above picture.
In serial line over 500 mt, connect a line termination resistor (Rt=100Ω - 120Ω) between the two
twisted pair cables leading from the converter at the end of the network (last connected instrument).
It’s recommended to use always twisted pair cable with minimum cross-section of 0.36mm
2
(22AWG)
and capacity less than 60 pF/m.
8.4.3) 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 = 100Ω C = 33µF.
The max length of the stubs is 20cm.
RS232/RS485
converter
Max 32 EMA; max 1200
N
L N
S1 S2 S1 S2 S1 S2
I1 I2 I3
L1V
L2V
L3V
Vaux
Do2-
Do2+
Di1+
Di1-
Di2+
Di2-
CE
N
L N
S1 S2 S1 S2 S1 S2
I1 I2 I3
L1V
L2V
L3V
Vaux
Do2-
Do2+
Di1+
Di1-
Di2+
Di2-
CE
Di1+ Di1- Di2+ Di2- Di1+
Di1-
Di2+ Di2- A
B
Do1- Do1+ A B Do1- Do1+
A
B
Do1 - Do1 + A
B
Do1 - Do1 +
Tx Rx gnd
Tx Rx gnd
Tx Rx gnd Tx Rx gnd
Rt
Max 32 EMA; max 1200 mt
RS232
A
B
Di1+
Di1-
Di2+
Di2-
A
B
Di1+
Di1-
Di2+
Di2-
A
B
N
L N
S1 S2 S1 S2 S1 S2
I1 I2 I3
L1V
L2V
L3V
Vaux
Do2 -
Do2 +
Di1+ Di1- Di2+ Di2-
A
B
CE
N
L N
S1 S2 S1 S2 S1 S2
I1 I2 I3
L1V
L2V
L3V
Vaux
Do2 -
Do2 +
Di1+ Di1- Di2+ Di2-
A
B
CE
Do1-
Do1-
Do1+
Do1+
Do1- Do1+ Do1- Do1+
RS232/RS485
converter
Tx Tx Rx Rx gnd
gnd
Tx Rx gnd Tx Rx gnd

Contrel EMA90 Specifications

General

Brand	Contrel
Model	EMA90
Category	Measuring Instruments
Language	English