User Manual

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Siemens Building Technologies VISONIK Building Process Station BPS / NetBPS CM2N8305en
Landis & Staefa Division 05.10.2000
Technical design
The PRV2… basic unit uses AC 24 V safety extra-low voltage "SELV" or protection by
extra-low voltage "PELV" as per HD 384.
The basic units with P-bus connection supply DC 24 V to the connected I/O modules
via the P-bus. The basic unit's load by one I/O module is indicated with load units at
12.5 mA each. The maximum load for the basic unit types with P-bus is available in
section "Type summary".
Measures pertaining to functional and system safety of the BPS/NetBPS:
Type Property
System clock The system clock is independent of the processor and
integrated in ASIC (real-time clock). In the event of operating
voltage failure, a battery continues to supply the clock.
Switch-on response Following activation of the supply voltage, the BPS/NetBPS is
ready for operation after 5 seconds.
Data storage in the
event of voltage failure
The following functions are maintained for at least 60 days by
means of a battery in the case of a voltage failure:
− Time and date.
− Microprocessor supervision (watchdog).
− Page recognition of the operating cards.
Plant application programs, configuration and process data.
Processor supervision The microprocessor's operation is supervised via a watchdog.
If the microprocessor is blocked by any event, the supervision
function triggers a restart of the processor system (software
reset).
Response in the event
of faulty operation
In the case of low voltage or voltage failure, the processor
system of the BPS/NetBPS executes a controlled reset.
The P-bus and any communication lines become passive, i.e.,
all sending functions are deactivated.
After operating voltage restoration, a restart occurs to reload all
previously defined functions.
BPS failure
The connected I/O modules turn passive.
Response without
program card
Without a program card, the BPS/NetBPS neither issues
commands via the P-bus nor the COM cards.
Removing the
electronics unit
Do not remove the electronics unit from the housing while
voltage is applied. If you must do so, however, construction
and switching technology measures are designed to prevent
data loss or damages to the unit's electronics.
Short-circuit strength The P-bus is short-circuit proof.
Protection from false
wiring
Interchanging P-bus lines does not damage the unit.
Inadvertent supply of AC 24 V to the P-bus connecting
terminals does not result in unit damages.
Operating voltage
AC 24 V
I/O module supply
System reliability