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Siemens
Heating and D.h.w. Controller RVL481
CE1P2541en
Building Technologies
25 Function block "Service functions and general settings"
20.05.2008
25.5.4 Bus power supply
In interconnected plants with a maximum of 16 controllers, the bus power supply may
be decentralized, that is, power may be supplied via each connected device. If a plant
contains more than 16 devices, a central bus power supply is mandatory.
On each connected device, it is then necessary to set whether the data bus is powered
centrally or decentrally by each controller.
With the RVL481, this setting is made on operating line 179. The display shows the
current setting as SET and the current bus power supply status as actual.
Display Bus
power
supply
SET
0
Bus power supply is central (no power supply via controller)
SET
A
Bus power supply is decentral via the controller
ACTUAL
0
Presently no bus power supply available
ACTUAL
1
Bus power supply presently available
The word BUS appears on the display only when the bus address is valid and when
bus power supply is available. This means the display indicates whether or not data
traffic via the data bus is possible.
25.5.5 Bus loading number
The bus loading figure E for the LPB of the RVL481 is 7. The total of all E-numbers of
the devices connected to the same bus may not exceed the limit of 300.
25.6 Heat demand output DC 0…10 V
Using the DC 0…10 V heat demand signal (terminals Ux–M), the RVL481 can transmit
the heat demand to other devices.
The heat demand corresponds to the heat requisition in °C and – in terms of value – is
identical with the heat requisition that reaches the precontroller via the data bus (LPB).
The temperature value of the heat demand corresponding to 10 V can be set via oper-
ating line 181.
Voltage signals:
Voltage
Temperature when operating
line 181 = 80 °C
Temperature when operating
line 181 = 130 °C
DC 0 V
0 °C
0 °C
DC 5 V
40 °C
65 °C
DC 10 V
80 °C
130 °C
