Powerware FCC 15 manual Wiring the Modbus Card, Two-Wire Networks

Chapter 3 Wiring the Modbus Card

The Modbus Card provides an easy path for integrating a Powerware UPS into an RS-485 Modbus network and also provides isolation of the communication between the UPS and the RS-485 Modbus network.

You can use the DB-9 port or terminal strip on the Modbus Card to wire into a two-wire or four-wire network.

Two-Wire Networks

The Modbus Card’s default configuration is for two-wire, half-duplex, RS-485 networks. Figure 6 shows a detailed view of two-wire connections using the Modbus Card terminal strip.

Slave Device #1

T-- R-- T+ R+ Gnd

Master Device

RT *

	UPS with
Slave Device #2	Modbus Card	RxD+	RxD–
			RT *
T-- R-- T+ R+ Gnd

T--

R--

T+

R+

Gnd

*See Note

Figure 6. Two-Wire RS-485 Modbus Network

NOTE Only one transmission pair is used. It is not necessary to jumper the unused pair together (this connection is made internally). Belden 9841 or equivalent cabling (a single twisted-pair shielded cable with ground) is recommended.

NOTE If the Modbus Card is the last device installed in the network chain or the length of the network cable is excessive, termination needs to be enabled (see page 10).

EATON Powerware® Modbus® Card User’s Guide S 164201376 Rev C www.powerware.com 7