Yokogawa PR300 Power and Energy Meter - Manual (Page 21)

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<Toc> <Ind> <2. Setup>
IM 77C01E01-10E
2.3 Wiring for Communication
Connect a higher-level device with the PR300 for using the communication func-
tions. The wiring procedures and precautionary notes are as follows.
2.3.1 Wiring for RS-485 Communication
For a common PC, the RS-485 interface is not directly connectable. Use a ML2 RS232C/
RS485 converter for wiring.
WARNING
To avoid an electric shock, be sure to turn off the power supply source to the equipment
involved before you start wiring.
Use crimp-on terminals at cable ends.
Before you start wiring, read the user’s manual of each device.
5
4
6
3
PR300
(with RS-485
communication function)
PR300
(with RS-485
communication function)
PC
Terminator
120 Ω 1/4W
Terminator (built-in)
120 Ω 1/4W
RS-232C
straight cable
JIS Class D (3) grounding
(grounding resistance
of 100
Ω or less)
JIS Class D (3) grounding
(grounding resistance
of 100
Ω or less)
Communication cable Communication cable
A ؊
B ؉
SG
A ؊
B ؉
SG
18
19
20
17
18
19
20
Wthen terminating on
wiring, short-circuit
terminals 17 and 18 .
(RS232C/RS485 converter)
Note: Use UL Listed RS-232C/RS-485 converter if the converter has AC/DC power supply input; this is
optional for converters supplied by a Limited Power Source with input voltages less than 30 V AC or
60 V DC and which are separated from mains by double or reinforced insulation.
Communication cable: Shielded twisted pair cable (AWG24-eqivalent size)
Recommended terminals: See the PR300 Power and Energy Meter User’s Manual (electronic manual).