Eltako – The System in the Building – Operating manual for Series 14 RS485 bus DIN rail mounted devices
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Bus gateway BGW14 and 4-wire sensors
Functional principle:
Data transmission and power supply take place over the 4-wire bus with a 12 VDC mains adapter. The bidirectional bus gateway
is used to feed control signals from connected bus sensors to the RS485 bus and output feedback signals (for display device). Up
to 16 bus sensors (BUTHxx, BTFxx, BTRxx and BBHxx) can be connected to the RSA/RSB terminals.
Connection is by means of conventional telephone wire J-Y(ST)Y-2x2x0,8mm². Data from max. 128 sensors can be fed to the
RS485 bus by max. 8 BGW14 devices. Addresses are generated from a basic address set at rotary switch BA and a set sensor
address of the connected sensors.
The BGW14 queries all connected sensors cyclically and the sensors reply with a data telegram. Data is compared to the previous
data; data is only output to the RS485 bus if there is a change. If data does not change, the connected sensors output status te-
legrams cyclically every 5 minutes.
Two different signal types can be selected on the clock thermostats BUTH55 and BUTH65.
Temperature FHK mode
EEP A5-10-06 for direct teach-in to a heating/cooling actuator
Temperature/humidity mode
EEP A5-10-12 if a visualisation software is used, e.g. GFVS
Connections and wiring:
Use the enclosed fixed bridge to integrate the BGW14 in Series 14. In addition, connect the HOLD terminal to all the other HOLD ter-
minals of the devices in the bus.
The bus gateway BGW14 provides a separate RS485 bus for the sensors and is connected to the RSA and RSB terminals. The re-
quired 12 VDC power supply for all sensors must be supplied from a separate switching power supply unit SNT12/230V-12V DC
which is connected to the + and - terminals of the sensors. Connect with the correct polarity! Here you can select any topology for
the 4-wire connection. The permitted total line length is 1000 m.
The second 120 ohm terminal resistor enclosed with the BGW14 must also be connected to the RSA/RSB terminals of the remotest
sensor. In a star-shaped wiring topology where the BGW14 is at the centre, the terminal resistor must be removed from the RS ter-
minals. The two terminal resistors must then be connected to the last device on the two longest stubs.
9. Bus gateway BGW14 and 4-wire sensors
(temperature and motion/brightness)
Funktions-Drehschalter
Standard setting ex works.
Bus gateway BGW14
Temperature sensor Motion detector
Room temperature
controller
Clock thermostat
