Panasonic HL-C2 Series, User Manual, Page: 15 / 278

Preface
13

Precautions for positive ground environment
The GND terminals of 24VDC (-) and USB port, SG of RS-232C, and
COMMON terminal (-) of the input / output circuit are connected inside the
HL-C2. The FG terminal, USB port connector shell, RS-232C connector shell
and Ethernet connector shell are also connected inside the HL-C2. Make sure
that there is no potential difference from externally connected devices such as
a PC and PLC.
PC HL-C2
RS-232C/
USB GND
PLC
RS-232C /
USB GND
GND
DC 24V (+)
DC 24V
FG
FG
DC 24V (-)
DC 24V (+)
DC 24V
DC 24V (-)
If the HL-C2 is used in a positive-grounding environment, power supply
(24VDC) can become short-circuited via the GND terminal of PC or USB,
thus resulting in a malfunction.
・
Do not ground the positive (+) terminal of the HL-C2.
・
When grounding the positive side of the power supply (24V DC) to the
equipment, use a separate power supply (24V DC) for the HL-C2 and
insulate the HL-C2.