Rockwell Automation 1440-SPD02-01RB XM-220 Dual Speed Module - Manual (Page 20)

Publication GMSI10-UM004B-EN-P - May 2010
12 Installing the XM-220 Dual Speed Module
24V Common Grounding
24V power to the XM modules Must be grounded. When two or more power
supplies power the XM system, ground the 24V Commons at a single point,
such as the ground bus bar.
Transducer Grounding
Make certain the transducers are electrically isolated from earth ground. Cable
shields must be grounded at one end of the cable, and the other end left
floating or not connected. It is recommended that where possible, the cable
shield be grounded at the XM terminal base (Chassis terminal) and not at the
transducer.
DeviceNet Grounding
The DeviceNet network is functionally isolated and must be referenced to
earth ground at a single point. XM modules do not require an external
DeviceNet power supply. Connect DeviceNet V- to earth ground at one of the
XM modules, as shown in Figure 2.6.
IMPORTANT
If it is not possible or practical to ground the -24Vdc
supply, then it is possible for the system to be installed and
operate ungrounded. However, if installed ungrounded
then the system must not be connected to a ground
through any other circuit unless that circuit is isolated
externally. Connecting a floating system to a non-isolated
ground could result in damage to the XM module(s)
and/or any connected device. Also, operating the system
without a ground may result in the system not performing
to the published specifications regards measurement
accuracy and communications speed, distance or reliability.
IMPORTANT
The 24V Common and Signal Common terminals are
internally connected. They are isolated from the Chassis
terminals unless they are connected to ground as described
in this section. See Terminal Block Assignments on page 18
for more information.