Viessmann PLC VITOCAL 350-HT PRO Service Instructions For Contractors page 29

Communication
(cont.)
Terminal Assignment
5 Termination
6 /RX/TX output
7 RX/TX output
8 Termination
Termination
■ The internal terminator must be activated if the heat
pump is connected to the start or end of the RS485
bus.
Two wire jumpers must be used for this purpose:
Connect terminals 5 and 6 to each other
–
Connect terminals 7 and 8 to each other
–
Transmission cables
■ Signals RX/TX and /RX/TX are required for transmis-
sion
RX/TX and /RX/TX are connected 1 to 1 with the
■
opposite side. GND must be connected to the data
cable screen on at least one side
■ For equipotential bonding, GND can be connected
on both sides.
In the case of potential differences, GND may be
■
connected on just one side. If the difference in poten-
tial is greater than 2 V, galvanic separation may be
required.
■ The data cable must be twisted and screened.
Modbus connection via Ethernet TCP
■ Modbus data transfer should always be carried out
via an Ethernet.
Installation of a separate data cable is not required.
RS485 converters for the PC connection are not
required.
Configuring the system
29