Emerson E2 - Manual (Page 81)

ECT MODBUS The RS485 Network and Hardware Setup • 6 - 21
1. Connect the MODBUS Network to the RS-485 Connector on the
E2 PIB board (Belden 8641 recommended).
2.
3. Position the three termination jumpers to the UP (terminated)
position to provide RS-485 termination at the E2.
4. Do not connect the shield of the MODBUS network to the E2 PIB
center terminal. Instead, use a 100 ohm ½ watt resistor to connect
the MODBUS cable shield to earth ground.
5. At each device, wire the MODBUS cable to the RS-485 +/- terminals
and connect the MODBUS shield to the pin termi
nal.
6. Terminate the end of the MODBUS network at the last device on
the daisy chain with the MODBUS termination block (P/N 535-2711),
or by connecting a 150 ohm resistor between the MODBUS
+/- terminals.
For more information, please refer to the XR35CX user manual
-
and the XR75CX user manual - P/N 026-1203 P/N 026-1210.
Note to wire the RS-485 +/- polarity at the E2 in the reverse of
the XR35CX or XR75CX device.
18
NOT TERMINATED TERMINATED
RS-485 I/O or MODBUS Net
HOT KEY
16 17 18 19 20 21 22 23 24
1 2 3 4 5 6 7 8
XR35CX, XR75CX TO E2
INSTALLATION GUIDE
0V +
RS-485 -2A
0V +
RS-485
637-4890 COM4 ON E2 PIB
BELDEN 8641
100 OHM
½ WATT
TO DEVICE
EARTH GROUND
CONNECTION
RESISTOR
MODBUS TERMINATION
BLOCK (P/N 535-2711)
150 OHM
TERMINATE LAST DEVICE ONLY
TERMINAL XR35CX/XR75CX
MODBUS TERMINAL
BLOCK
FROM OTHER RS-485
MODBUS DEVICE
0V +
RS-485 -2A
0V +
RS-485
637-4890 COM4 ON E2 PIB
OBSERVE WIRE
COLOR POLARITY
SHIELDED TWISTED
PAIR
RECOMMENDED
BELDEN 8641
REVERSE POLARITY OF
+/- ON RS-485 CABLE
FROM E2 TO DEVICE
100 OHM
½ WATT
WIRE BLACK TO +
WIRE WHITE TO
_
WIRE WHITE TO +
WIRE BLACK TO
_
XR35CX/XR75CX
XR35CX / XR75CX
DEVICE
COM 4