Emerson FB2200 Flow Computer Instruction Manual
D301784X012
March 2019
80 I/O Configuration and Wiring
3.8 Wiring a Digital Output to the Optional Relay
The flow computer supports two optional electro-mechanical relays for switching on/off external
circuits or devices. If you order this option, the relays ship from the factory mounted to the top of
the battery compartment inside the flow computer enclosure.
You can wire a relay to an isolated DO (Figure 3-17). You must also use the isolated GND and
provide 24V to power the relay. To attach a wire, insert it into the connector and tighten the
adjacent screw to secure it. The NO and COM wires go to the external circuit or device.
Figure 3-17. Relay Wired to Isolated DO
Alternatively, you can wire a relay to a non-isolated DO (Figure 3-18). In that case, you must use the
non-isolated GND and provide 24V to power the relay. To attach a wire, insert it into the connector
and tighten the adjacent screw to secure it. The NO and COM wires go to your external circuit or
device.