Situation 1
+
−
RFU6xx/RFH6xx
F
CDB/CDM
+
−
+
V
S
−
−
1
2
3
2
F
CDB/CDM
RFU6xx/RFH6xx
+
+
−
−
+
V
S
−
−
1
+
2
3
2
+
Figure 34: Reversal of the polarity of the supply voltage: no effect on the RFID device (see
requirements)
1
Fuse in the connection module: 2 A (CDB650-204, CDM420-0006)
2
Blocking diode
3
Connection module
The housing of the RFID device is connected to functional earth. In the optional CDB or
CDM connection module, a fuse acts as an overload protection against too high current
when the supply voltage is applied correctly. A further blocking diode also serves as a
reverse polarity protection.
If the polarity of the supply voltage is reversed, the blocking diodes block the negative
voltage on the positive pole of the RFID device.
NOTICE
The polarity reversal will not cause any damage provided the following two require‐
ments are met for the device:
•
The negative pole of the applied supply voltage is not connected to functional
earth as a common reference potential
•
The device is not connected in an electrically conductive manner to any other
peripheral devices that use the same reference potential. Neither through its
metal housing or over other cables (signal relative to GND, shielding).
6
ELECTRICAL INSTALLATION
62
O P E R A T I N G I N S T R U C T I O N S | RFU63x, RFU65x
8014335/ZTL9/2018-10-14 | SICK
Subject to change without notice
