5.6.2 RS-485 - network design and interface parameter
Please ensure the correct connection; i.e. "A (D+)" must always be connected to "A
(D+)" of the next devices. The same applies to "B (D-)" .
In addition, a "GND" connection must be established, as dissimilar potential (over 10 V!)
will lead to the destruction of the RS-485 interface (e.g. lightning).
G
N
D
D
+
D
-
G
N
D
D
+
D
-
16.04.2008
v_modbus_geraete_anschluss.vsd
general example for Modbus device connection
The data line must be connected from one device to the next. No other type of wiring is
allowed! Always use only two wires of one lead (twisted pair) for the connection.
Examples for Modbus connection
Recommended wire types
1. CAT5 / CAT7 cables
2. J-Y (St) 2x2x0.6 (telephone cable)
3. AWG22 (2x2 twisted pair)
Information
•
Pay attention to suf
fi
cient distance from powerlines and motor wires (min.
20 cm).
•
Do not use wire shield.
•
Except the data link "A (D+)", "B (D-)" the "ID1 - ID2" and the "GND" connection
may no further cable cores of the data line be used.
•
A maximum of 63 users can be connected directly with each orther in automatic
adressing.
•
Max allowed wire length 1000 m (CAT5/7 500 m).
Default interface parameter
Baudrate
=
19200
Bits
=
8
Parity
=
Even (None, exception of devices agriculture)
Stop bits
=
1
Handshake
=
none
Operating Instructions
NETcon
A-G-102ANE
Electrical installation
L-BAL-E156-GB 2105 Index 004
Part.-No.
13/32
