Controllogix Analog Input Module 1756-IF16CIS allen-bradley

The 1756-IF6CIS module offers an internal power source on each channel. The
source is current limited to 28 mA and allows the module to power a two-wire
transmitter directly without the need for an external power supply. The
transmitter can then vary the current to the analog input in proportion to the
process variable being measured. The inclusion of an internal on-board current
source saves you the expense of extra power supplies and greatly simplifies the
interface wiring to field devices.
In addition to supplying loop power to two-wire transmitters, the module can
also accommodate current loops powered by an external supply and loops using
four-wire transmitters.