Table of Contents
Advertisement
M-Bus Master MultiPort 250D
4.1
Special features of M-Bus Master MultiPort 250D
M-Bus Master MultiPort 250D has been designed with the newest cable driver technology, and is, therefore, rather
insensitive to the capacity of the M-Bus network.
Thus, designing an M-Bus network to be used together with M-Bus Master MultiPort 250D, the limiting factor as to
possible cable length will primarily be the cable resistance in the network.
4.2 Electrical conditions in an M-Bus network
According to EN 13757-2, the maximum output voltage from an M-Bus Master must not exceed 42 V. The output voltage
from M-Bus Master MultiPort 250D is 41 V.
• If the voltage measured over terminals 24-25 is 24 V or more at the most distant meter, there is a high degree of
certainty that all meters can be read.
• If the voltage is between 20 and 24 V, it will probably be possible to read all meters.
• If the voltage is between 18 and 20 V, the meter may be read.
• If the voltage is below 18 V, it is most likely that the meter cannot be read.
There must be no communication on the M-Bus network when the above measurement is made.
4.2.1
M-Bus modules
Each M-Bus module loads the M-Bus network too. According to the standard, an M-Bus module should load the
network with 1 unit load (UL) corresponding to 1.5 mA. Some modules, however, load with up to 4 UL.
Capacitively the load of an M-Bus module is 0.5 – 1 nF.
The number of connected M-Bus slaves is shown on the display of M-Bus Master 250D. Please note that it is not
possible to show the exact number of connected slaves. This is due to tolerances in the slaves.
4.3 Installation parameters
The following parameters are essential to the possible cable length of an M-Bus network.
18
Kamstrup A/S • 5512853_C1_GB_01.2017
Hide quick links:
Advertisement
Table of Contents
