The UI current loop fail-safe jumpers are on the circuit board under the controller cover near the UI terminals. When a UI is defined (in the system software) as a 4-20 mA Analog Input and the UI’s current loop jumper is in the Disabled (default) position (Figure 1), the 4-20 mA current loop circuit opens whenever power to the controller is interrupted or off.
Setting the current loop jumper to the Enabled position (Figure 1) connects an internal 100 ohm resistor across the UI terminals, which maintains the 4-20 mA current loop circuit even when power to the controller is interrupted or off.