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 1), the 4 to 20 mA current loop circuit opens whenever power to the expansion module is interrupted or off.
Figure 1. Current loop jumper positions
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 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.