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 2 digital inputs for the connection of potential-free contacts.
The operating action of the contacts (active closed or active open) can be parameterized.
The M-bus central unit can detect the following types of fault:
 Messages delivered to the digital inputs: Immediate delivery of alarms
 Failures of M-bus devices: Cyclic readout of device data by the central unit, de-
pending on the setting made (refer to "Readout": Readout interval, alarm interval).
Failure of an M-bus device is signaled as an alarm only after the central unit has
failed to make a readout
 Error messages from the M-bus devices: Since the M-bus is a single master slave
bus, the M-bus 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 setting made
(refer to "Readout": readout interval, alarm interval).
A fault detected at an M-bus device is signaled as an alarm only after the central
unit has completed its readout
 Device error of the M-bus central unit: Immediate delivery of alarms
The faults can be weighted and assigned to the following types of output devices:
 Alarm LED
 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…".
Rectification of a fault is not signaled to the control center.
Digital inputs
Alarms