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18 Kmstrup A/S • 5512853_C1_GB_01.2017

M-Bus Mster MultiPort 250D

4.1 Specil fetures of M-Bus Mster MultiPort 250D

M-Bus Mster MultiPort 250D hs been designed with the newest cble driver technology, nd is, therefore, rther

insensitive to the cpcity of the M-Bus network.

Thus, designing n M-Bus network to be used together with M-Bus Mster MultiPort 250D, the limiting fctor s to

possible cble length will primrily be the cble resistnce in the network.

4.2 Electricl conditions in n M-Bus network

According to EN 13757-2, the mximum output voltge from n M-Bus Mster must not exceed 42 V. The output voltge

from M-Bus Mster MultiPort 250D is 41 V.

• If the voltge mesured over terminls 24-25 is 24 V or more t the most distnt meter, there is  high degree of

certinty tht ll meters cn be red.

• If the voltge is between 20 nd 24 V, it will probbly be possible to red ll meters.

• If the voltge is between 18 nd 20 V, the meter my be red.

• If the voltge is below 18 V, it is most likely tht the meter cnnot be red.

There must be no communiction on the M-Bus network when the bove mesurement is mde.

4.2.1 M-Bus modules

Ech M-Bus module lods the M-Bus network too. According to the stndrd, n M-Bus module should lod the

network with 1 unit lod (UL) corresponding to 1.5 mA. Some modules, however, lod with up to 4 UL.

Cpcitively the lod of n M-Bus module is 0.5 – 1 nF.

The number of connected M-Bus slves is shown on the disply of M-Bus Mster 250D. Plese note tht it is not

possible to show the exct number of connected slves. This is due to tolernces in the slves.

4.3 Instlltion prmeters

The following prmeters re essentil to the possible cble length of n M-Bus network.

Kamstrup M-Bus Master MultiPort 250D User Manual

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