Basic Documentation

20/58
Siemens Bus operator unit RMZ792 Series B CE1P3113en
Building Technologies 4 Supply 07.07.2011
4.4 Troubleshooting
Faults Cause / Solution
Bus operator unit does not start.
Bus operator unit restarted cyclically.
KNX bus blocked.
Operating values of bus devices not
displayed properly or cannot be
changed.
Background illumination of display very
low.
• Wrong polarity CE+ / CE–
• Insufficient power supplied by KNX
bus (undersized bus supply, bus
voltage too low).
• Wrong switch setting ("KNX"/EXT") or
switch in illegal intermediate position.
• RJ45 plug not snapped in (no
contact).
Control unit signals extension modules'
failure, some plant parts fail.
The slider is set to "EXT" and the bus
operator unit was plugged in during plant
operation.
Solution:
1. Acknowledge or reset fault status
messages.
2. Switch off operating voltage to the
control unit, then plug in bus
operator unit and switch on
operating voltage
or
3. Plug in the bus operator unit to a
control unit without extension
modules (switch off operating
voltage prior to plugging in, then
plug in bus operator unit, and then
switch on operating voltage).
Possible cases