The Cs31 System Bus - ABB 07CR41 Operating Manual

4.1.5

The CS31 system bus

3
The CS31 system bus is an RS 485 serial bus and consists of a shielded twisted 2-wire cable.
This bus is a master slave bus and only supports a single master.
Use an AWG 24 (≥ 0.22 mm²) twisted pair with joint shielding. 0.5 mm
recommended.
The maximum length is 500 m.
The same cable type should be used for the whole system bus set-up.
Bus interruptions should be avoided, e.g. for cabinet cable connections for instance, otherwise
connection should be made to the same side of the terminal block (see Figures 7 and 8 on
page 4–5).
Warning: STAR configuration of the bus is not permitted!
(see Figures 9 and 10 on page 4–5).
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Cabling
The basic and remote units may be connected at any point of the bus:
- bus 1 to bus 1
- bus 2 to bus 2
- shielding (preferably braided) on terminal 3 of terminal block 1 and earth connected
at the master level (cable < 0.10 m)
The bus should be terminated with a 120 Ω 1/4 W resistor connected to the bus ends. The
twisted pair should be symmetrical (see Figures 11a and 11b on page 4–5).
As the CS31 system bus is isolated, it is possible to connect elements with different voltage
power to the bus.
Using bus amplifiers, the max. bus length may be extended to 2000 m. You can find the
relevant information in the AC31 System Description (Ordering Number 1SAC 1316 99 R0201)
under the AC31 bus amplifiers NCB and NCBR.
Installation 4 – 6
= ∅ 0.8 mm is
2
Advant Controller AC 31 / Issued: 08.99