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1.
Determine the physical location of the expansion module on the SA or FC bus.
2.
Determine if the expansion module must be set as a terminating device on the bus.
Note: The EOL termination rules for SA buses and FC buses are different. Refer to the
following documents depending on your system (FX or BCPro): FX-PC Series Controllers MS/
TP Communications Bus Technical Bulletin (LIT-12011670) or MS/TP Communications Bus for
BCPro™ System Technical Bulletin (LIT-12011908) for detailed information regarding EOL
termination rules and EOL switch settings on SA and FC buses.
3.
If the expansion module is a terminating device on the FC bus, set the EOL switch to ON. If the
expansion module is not a terminating device on the bus, set the EOL switch to OFF.
When an expansion module is connected to power with its EOL switch set to ON, the amber
EOL LED on the expansion module cover is lit.
UI current loop jumpers
The UI current loop fail-safe jumpers are on the circuit board under the expansion module cover
near the UI terminals. When a UI is defined (in the system software) as a 4 to 20 mA Analog Input
and the UI's current loop jumper is in the Disabled (default) position (Figure 12), the 4 to 20 mA
current loop circuit opens whenever power to the expansion module is interrupted or off.
Setting the current loop jumper to the Enabled position (Figure 12) connects an internal 100 ohm
resistor across the UI terminals, which maintains the 4 to 20 mA current loop circuit even when
power to the expansion module is interrupted or off.
Important: Current Loop jumpers must be in the Disabled (default) position for all UIs that are
not set up to operate as 4 to 20 mA analog inputs.
Current loop jumper IDs
The following table identifies the current loop jumpers associated with each UI on the FX-PCX2721
expansion module.
Table 8: FX-PCX2721 UI Inputs and jumper labels
Universal Input label
IN1
IN2
IN3
22
FX-PCX2721 Expansion Input/Output Module Installation Instructions
Figure 12: Current loop jumper positions
Jumper label on circuit board
J1
J2
J3
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