E2 Modbus Network Wiring - Emerson XR75CX Installation And Operation Manual

17 E2 MODBUS Network Wiring

• Connect the MODBUS Network to the RS485 Connector on the E2 PIB board (Belden 8641 recommended).
• Note to wire the RS485 +/- polarity at the E2 in the reverse of the XR75CX devices.
• Position the three termination jumpers to the UP (terminated) position to provide RS485 termination at the E2.
•Do not connect the shield of the MODBUS network to the E2 PIB center terminal. Instead, use a 100 ohm 1/2 watt
resistor to connect the MODBUS cable shield to earth ground.
• At each XR75CX device, wire the MODBUS cable to the RS485 +/- terminals and connect the MODBUS shield to
the pin 18 terminal.
• Terminate the end of the MODBUS network at the last XR75CX device on the daisy chain with the MODBUS ter-
mination block (P/N 535-2711), or by connecting a 150 ohm resistor between the MODBUS +/- terminals.
MODBUS TERMINATION
BLOCK 535-2711 150 ohm
Terminate last device only
Figure 17-1 - XR75CX to E2 MODBUS Network Wiring
22 • XR75CX I&O Manual
COM4
EARTH GROUND CONNECTION
100 Ohm
½ Watt
REVERSE POLARITY OF +/- ON RS-485
CABLE FROM E2 TO DEVICE
026-1210 Rev 0 09-FEB-2011