Emerson XM678D, Руководство по эксплуатации и установке

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Auxiliary Output E2 MODBUS Network Wiring • 39
22 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 XM678D 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 XM678D device, wire the MODBUS cable to the RS485 +/- terminals and connect the MODBUS shield to
the pin 38 terminal.
• Terminate the end of the MODBUS network at the last XM678D device on the daisy chain with the MODBUS
termination block ( P/N 535-2711 ), or by connecting a 150 ohm resistor between the /- terminals.
Refer to Appendix A - Alternate MODBUS COM Wiring Method for E2, XR, XM, and XEV Devices .
(Technical Bulletin P/N 026-4148.)
Figure 22-1 - XM678D to E2 MODBUS Network Wiring
CAUTION! For the XR, XM, and XEV series of controllers, the shield wire must not come into contact with
any other wire or ground source. If contact with other wires or devices does occur, the 485 MODBUS network
will malfunction or connected devices will be damaged. This applies to all installations where the shield is tied
to ground through a 100 ohm ½ Watt resistor.