KW8M Eco-POWER METER (1A/5ACT input type)
10
3.5 RS485 Communication
・
When using shielded cable for the RS485 transmission line, ground one end.
Use a class D dedicated earth for grounding. Do not share a ground with other earth lines. (Fig.1)
・
Be sure to connect with daisy chain the RS485 transmission line between each unit.
Do not use a splitter. (Fig.2)
・
With a terminal station, RS485 (E) (No.10) and RS485 (-) (No.9) should be shorted.
*E terminal is not SG (signal ground) terminal. Do not ground shielded cable.
Recommended Cable
Use the transmission cables shown below for Eco-POWER METER RS485 communication system.
Conductor Insulator
Cable
Size
Resistance
(at 20
℃）
Material Thickness
Cable
diameter
Applicable cable
1.25 mm
2
(AWG16)
or more
Max.16.8
Ω
/km
Polyethylene
Max.
0.5 mm
Approx.
8.5 mm
HITACHI
KPEV-S
1.25 mm
2
×
1P
Belden Inc. 9860
Twisted-
pair
with shield 0.5 mm
2
(AWG20)
or more
Max.33.4
Ω
/km
Polyethylene
Max.
0.5 mm
Approx.
7.8 mm
HITACHI
KPEV-S
0.5 mm
2
×
1P
Belden Inc. 9207
VCTF
0.75 mm
2
(AWG18)
or more
Max.25.1
Ω
/km
PVC
Max.
0.6 mm
Approx.
6.6 mm
VCTF
0.75 mm
2
×
2C
(JIS)
Cable Section
Twisted-pair
with shield
VCTF
Notes
1) Use shielded type twist cables.
2) Use only one type of the transmission cables.
2) Do not mix different types of the cables.
3) Use twist pair cables under a bad noise environment.
(Fig.2)
Correct wiring
○
Incorrect wiring
×
Terminal Terminal
station
station
Conductor Insulator
Jacket
Shield
Jacket
Conductor Insulator
(
－
)
(
＋
)
(
－
)
(
＋
)
Shielded cable
To RS485 device
Shielded cable
Eco-POWER METER
General station
Class D grounding
Class D grounding
Eco-POWER METER
Terminal station
(Fig.1)
