Hitachi SJ Series, User Manual

Page: 494 / 786

14-3
Chapter 14 RS485 Communication

Connection
• When performing a connection, connect each
inverter in parallel as shown below. For the
terminating inverter, short-circuit between terminals
RP and SN. (When you execute RS485
communication on one inverter, short-circuit
between RP and SN likewise.) With the RP-SN
short-circuited, the termination resistor within the
control terminal block board becomes enabled,
which prevents reflection of signals.
• As for a cable to connect to TM2, use a shielded
twisted pair cable (0.5mm
2
). If the above
mentioned cable is not available, use the following:
• Single cable of 0.14 mm
2
to 1.5 mm
2
(0.14 mm
2
to 0.5 mm
2
to connect two same size
cables to one pole)
• Stranded cable 0.14 mm
2
to 1.0 mm
2
(0.14 mm
2
to 0.2 mm
2
to connect two same size
cables to one pole)
• For communication cables, use shielded cables.
• As for shields, it is recommended that a signal
ground (SG) of external control equipment is
connected to CM1 of an inverter as shown below.
• Stranded cable with rod terminal
0.25 mm
2
to 0.5 mm
2
(e.g. 1.25=3AF manufactured by J.S.T. Mfg. Co.,
Ltd.)
Cable stripping length 5 mm
Tightening torque 0.22·N
･
m to 0.25·N
･
m (screw size
M2)
!
External control
equipment
Termination
resistor
enabled
SG
Shield

+
Termination
resistor
Inverter
SP SN SP SN
C
M1
Inverter
RP
SP SN SP SN
C
M1
Inverter
RP SP SN SP SN
C
M1
Inverter
RP