ICP DAS USA I-7540D - Manual (Page 16)

Therefore, the i-7540D module supplies a jumper for users to connect the
terminator resistor or not. If users want to use this terminator resistor, please open
the i-7540D cover and use the JP3 jumper to activate the 120
Ω terminator
resistor built in the system, as in the figure 2-5. Note that the default setting is
active. And about the J3 jumper setting, please refer the table 2-5.
Figure2-5 XC100 I/O expansion board LAYOUT
Table 2-5 J3 Jumper Selection
Apply the termination
resistor(120Ω)
Don’t apply the termination
resistor
i-7540D CAN-Ethernet Gateway User’s Manual (Version 1.4, April/2008) 16