User Manual

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Building Technologies M-bus System CE1P5361en
HVAC Products 2 System components 08.02.2007
The M-bus central unit has 4 digital inputs for the connection of potential-free contacts.
When a contact closes, the M-bus central unit indicates an alarm.
The M-bus central unit identifies the following types of faults:
 Signals at the digital inputs: Immediate delivery of alarm messages
 Failures of M-bus and Siemeca™ AMR devices: Cyclic readout of data by the cen-
tral unit, depending on the setting made (refer to "Readout": Readout interval,
alarm interval). Failure of a device is signaled as an alarm only after the central
unit has failed to make a readout
 Error messages from the M-bus and Siemeca™ AMR devices: Since the M-bus is
a single master slave bus, the devices cannot by themselves send the fault status
messages to the central unit. Therefore, the central unit needs to cyclically query
the devices one by one. This query is made during readout, depending on the set-
ting made (refer to "Readout": Readout interval, alarm interval). A fault detected at
a device is signaled as an alarm only after the central unit has completed its read-
out.
Siemeca™ AMR devices send their data periodically to the radio nodes WTX16 or
WTT16. Only when the faults have been transmitted to the radio node can they be
read out by the M-bus central unit via radio node
 Faulty memory card, insufficient battery voltage, etc.: Immediate delivery of alarms
 Device error of the M-bus central unit: Immediate delivery of alarms
 A description of all faults that can be detected by the M-bus central unit is given in
section 8.7 "Error messages from M-bus devices and alarm messages delivered by
the OZW…".
The faults can be weighted and assigned to the following types of output devices:
 Indication of alarms
 Alarm relay
 PC with alarm software "ACS Alarm"
Each error code of the central unit can be assigned a priority (e.g. error code "01 Tv<Tr
or T outside value range" of the central unit in the above example has priority 0 as the
standard setting). Errors having priority 0 are not passed on to any output device. Er-
rors having priority 1 through 3 are passed on to the output devices, depending on the
setting made.
A description of all faults that can be detected by the M-bus central unit is given in sec-
tion 8.7 "Error messages from M-bus devices and alarm messages delivered by the
OZW…".
Faults that have occurred are displayed by the OZW… until rectified and acknowl-
edged. Acknowledgement is made by pressing the buttons or by routing the alarm to
the PC.
Rectification of faults is not signaled to the control center.
Digital inputs
Alarms