Rockwell Automation 1440-TTC06-00RE XM-362 Temperature Module - Manual (Page 15)

Publication GMSI10-UM008D-EN-P - August 2010
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When using a 3-wire configuration, the XM-361 compensates for resistance
error due to lead wire length. For example, in a 3-wire configuration, the
XM-361 reads the resistance due to the length of the wires and assumes that
the resistance of the other wire is equal. If the resistance of the individual lead
wires is much different, an error may exist. The closer the resistance values are
to each other, the greater the amount of error is eliminated.
To ensure that the lead values match as closely as possible:
• Keep lead resistance as small as possible and less than 50 ohms.
• Use quality cable that has a small tolerance impedance rating.
• Use a heavy-gauge lead wire which has less resistance per foot.
Power Requirements
Before installing your module, calculate the power requirements of all modules
interconnected via their side connectors. The total current draw through the
side connector cannot exceed 3 A. Refer to the specifications for the specific
modules for power requirements.
Figure 2.1 is an illustration of wiring modules using separate power
connections.
IMPORTANT
To ensure temperature or resistance value accuracy, the
resistance difference of the cable lead wires must be equal
to or less than 0.01 ohm.
ATTENTION
A separate power connection is necessary if the total
current draw of the interconnecting modules is greater than
3 A.