5.7
Connecting communication
The isolated RS-485 interface is available with four pins. It features an isolated,
bidirectional, balanced communication bus (A and B) and a connection for isolated
ground. The fourth pin is an AC coupled shield terminal. Typical connection is
through a shielded twisted-pair (STP) cable. The RS-485 connection is compliant
with TIA/EIA-485. The RS-485 serial port is shown in
GUID-66B567E8-9650-4F6E-A324-08783C27CDE6 V1 EN-US
Figure 27:
RS-485 4-pin terminal
Table 5:
RS-485 connector pins
RS-485 connector pin
Signal
Type
1
A_485
Data signal A (normal)
2
B_485
Data signal B (inverted)
3
SHIELD
AC coupled shield pin
4
GND_485
Common pin for A/B
•
Ensure the communication interfaces are properly connected.
The relay's communication interfaces are located on the lower left side of the
protection relay when viewing it from the rear.
The allowed tightening torque for the RS-485 interface is
0.15...0.20 Nm (0.1106...0.1475 ft lb).
See the technical manual for product-specific communication
interfaces.
5.7.1
Accessing Modbus termination jumper
Bus termination can be activated though a jumper on the PSU module that is
accessible when the plug-in unit is removed from the base casing.
1.
Locate the access hole to the jumper on the rear of the plug-in unit.
2.
Remove or attach the jumper using appropriate nose pliers.
2NGA000821 A
Section 5
Connecting
REX610
41
Installation Manual
