The M-Bus converters M095 and M096 may freeze occasionally if powered by an unsuitable low voltage stabilized power supply. The supply must meet the requirements of EN 61000-6-2 ed. 3:2006 (EMC for industrial environment), and EN 61000-4-11 ed.2:2005 (Voltage dips, short interruptions and voltage variations immunity tests).
For the converter to operate correctly, following requirements must be met:
- power supply rise time must be maximum 70 ms
- the rise (and fall) must be monotonous, in other words, during the rise time the voltage must not drop.
If the freezing problem should appear, the first choice is to power the M-Bus converters by a separate power supply or 24 V AC transformer which is not loaded by other circuits (I/O modules, DDC process stations, air damper actuators etc.) that may distort the power supply characteristics.
Converters supplied after September 16, 2015, are set up with another type of DC/DC converter which should not show the problems described above.