Installation Instructions

Installation
Wiring
1
A6V11478123_en_c 7 | 22
1.4 Wiring
1.4.1 Electrical grounding
Note the following grounding situation of the QBM97.
● QBM97 uses a non isolated RS485-Interface
● The reference of RS485 transceiver is connected to GND
● all GND pins are on the same potential
● if the Climatix controller and QBM97 are connected to the same power source,
take care to avoid miswiring between 24 V input and GND
The document "Modbus communication" (J3960) provides profound information
on Modbus grounding.
Transformer
Power-
supply
24V
0V
REF B- A+
Earth
Sensor module
Not isolated RS485
M
Situation
Consequences