Assembly- and Installation
Instructions
Lohberger Heiztechnik
GmbH
N28/HB N28/GB
Seite 33
Lohberger Heiztechnik GmbH, A-5020 Salzburg-Bergheim, Rechtes Salzachufer 40
Tel. 0662-450444-0, Fax-DW 9
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8.9
Examples for a bus system
8.9.1
RS485 Bus cabeling digital-room unit and bus module - wiring guidelines
Bus cable: minimum cross-section 0.5 mm ², with shielding (see section 8.8), eg
LI-YCY
or similar. For details, see wiring diagrams below.
Do not use unshielded cables! !
Do not lay transmission line to individual users! All users must be connected to a wiring
harness - for non-compliance a trouble-free operation can not be ensured.
On every last bus user in the wiring harness a 120 ohm, 0.5 watt terminating resistor
must be clipped to the lead of the bus cable between terminals A and B.
Bei Leitungslängen von über 200m oder wenn das Bus- Kabel parallel zu
Netzspannungsführenden Leitungen verlegt ist, nur Kabel mit verdrillten Adern-Paaren
(Feldbuskabel geschirmt 2x2xAWG24) verwenden. For cable lengths of more than 200m,
or if the bus cable is laid parallel to mains carrying cables use only cables with twisted
wires pairs (shielded fieldbus cable 2x2xAWG24).
Wenn If digital room units are powered from the bus line with a wire cross section of 0.5
mm ², the cable to the power supply must not be longer than 50m (in case of excessively
long cable lengths, the voltage drop is too high). Fit the power supply in the course of the
bus line in a suitable place of the elec. installation (installation box or the E-distribution)
(see below).
Technical data of external power supply: 8-9V DC (direct current, stabilized), current per
supplied room unit 0.25 A. Example: If two room units are supplied the power supply
must deliver at least 0.5 A.
The I / O board (motherboard boiler) can supply max 2 digital-room units, the maximum
cable length (up till 2nd room unit) in this case is 50m (with a wire cross section of 0.5
mm ²). If longer cable lengths are required, the wire cross section must be increased.
Electrical data for the cross section calculation: 8V DC, 0.25 A;
If the supply of digital room units is not via the bus cable, the maximum cable length
(from the boiler to the last device) 800m.
In addition, the rules of the applicable electrical installation regulations (OVE, VDE, etc.)
are to be observed.
