General
6 720 802 419 (2012/06) en
8
3.9
CAN-BUS
The various circuit boards in the heat pump are joined by a
communications cable, CAN-BUS. CAN (Controller Area Network) is a
two-wire system for communication between microprocessor based
modules/circuit boards.
A suitable cable for external laying
is cable ELAQBY/LIYCY (TP)
2x2x0.5. The cable must be twisted pair type and screened. The screen
must only be earthed at one end and to the chassis.
Maximum cable length is 30 m.
CAN-BUS cable must
not
be laid alongside power supply cables.
Minimum distance 100 mm. They may be laid alongside sensor cables.
The connection between the circuit boards is by four wires, because the
12V-supply between the circuit boards must also be connected. The
circuit boards have markings for both the 12V and CAN-BUS
connections.
Switch Term
is used to mark the start and end of a CAN-BUS loop.
Ensure that the correct circuit board is terminated and that all other
switches are in the opposite position.
Fig. 2
[GND]
Earth
[CANL] CAN low
[CANH] CAN high
[+12V] Connection 12V
[EWP]
Heat pump
CAUTION:
Interference.
B
The CAN-BUS cable must be screened and laid
separately from the power cable.
CAUTION:
Do not mix up the 12V and CAN-BUS
connections!
The processors are destroyed if 12V is connected to the
CAN-BUS.
B
Check that the four cables are connected to the
contacts with the corresponding marking on the
circuit board.
6 720 614 967-31.2I
CAN-BUS
CAN-BUS
