Domestic Hot Water Heat Pump Service Manual
38
8.0 Modbus
As standard the Toshiba Domestic Hot Water Heat Pump units are supplied with a ModBus
controller. The controller provides a secondary port to be connected to a system network thanks to
an RS485 bus. The controller has the ability to communicate without an amplifier. The length of
the bus does not exceed 500m.
Description
Line
Spec.
Maximum
Length
(m)
Connection Destination
RS-485
connection
2 wire
shielded
500m
PCB
WF1
Pin 1
A
+RS485
Pin 2
B
-RS485
The following schematic shows the electrical connections for the Modbus operation
B
LU
B
(D
-)
L
N
L
N
0V
0V
L
L
0V
0~
10V
Input
BT3
EB1
0V
0V
0V
FM
BT2
BT1
0V
0V
L
N
PE
230VAC ~ 50Hz
0V
A
(D+
)
0V
B
LU
0~
10V
P
W
M
YE
L
High pressure switch.
Compressor STOP when
Pd ≥ 2.0MPa
Solenoid valve.
Solenoid ON for 2 min
before compressor
starts and during
system defrost
B
R
N
B
LK
N
BLU
BLK
BRN
B
R
N
B
LU
M
odbus
com
m
uni
cat
ion