Network extension · Introduction Comparison of network extension methods Controllers / Gateways,network extension

Controllers / Gateways,network extension

System description Dual masters repeaters in the centre of the machine allow an extension of the AS-icable by a further 100 metres in opposite directions. Distances of 200 metres can thus be linked. One of the advantages is that twice the number of AS-i participants can be connected. allow the cable length to be extended by a fur-ther 100 metres. The number of possible participants remains unchanged. Each repeater has a galvanic separation which divides the network into two segments. Each segment has its own voltage supply. The master segment can thus be supplied with voltage via AS-i power supply 1 and the segment after the repeater via AS-i power supply 2. This principle allows an increase in total current per AS-i network and improves the voltage drop.A repeater can also be used for safety reasons. A repeater is used to ensurethat a short circuit on the secondary circuit has no influence on the primary circuit. AS-i networks can thus be divided into electrically separated seg- ments. Each repeater has an internal propagation time which adds for series con-nection. This limits the number of repeaters to be used, see table below.3. 1. The termination plug at the end of the long cable minimises reflections.In case of only few participants it should be connected at the end of the cable since the voltage drop there increases with the connected load. An- other advantage of the bus termination is the improvement of the AS-i mes- sage quality for long cables and the use of Safety at Work components. 2. AS-Interface There are different ways to extend the AS-i cable. The specified one hundredmetres can be extended up to 600 metres in extreme cases. The following table shows the different possibilities and the different methods of cable extension. There are several solutions for an extension by a further 100 metres: The classic AS-i bus is designed for a cable length of 100 metres. Experi-enced users have found out that often systems with 130 metres and more function without any problems. However, AS-i has a free topology so that there is no general installation rule for these 100 plus “x” metres. In many cases long , non-terminated cables cause reflections which overlay the AS-i messages and cause faults and message repetitions.

Measure Extensionby Additionalpower supply= more currentfrom AS-i Electricalseparation Voltagedrop Max. no.of slaves: Cost / benefit*per slave(ranking) Comment Repeaters Dual masters100 m 100 myes yesyes yesuncritical uncritical62 1246.2 (4) 2.8 (2)max. 2 repeatersin series and max. 1 repeater for Safety at Work master in the centreTerminationplug check total current from AS-i and message quality Tuner100 m 100...150 mno nono nocritical critical62 620.95 (1) 6.13 (3)check total currentfrom AS-i and message quality
* Formula: (Unit cost / max. number of slaves)

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