Rockwell Automation 1771-N SERIES High Resolution Analog Module User Manual - Manual (Page 28)

2–10 Installing the Module
Publication 1771ĆUM127B-EN-P - December 2002
The 1771-NIS, 1771-NBSC and 1771-NB4S modules are
sourcing/sinking input modules. These modules can supply the
necessary loop power for 2-wire transmitters connected to the input.
All loop power functionality is contained within the analog module.
Examples of typical configurations are shown in Figure 2.6.
No external resistors are required.
Figure 2.6
Examples of Sourcing/Sinking Input Modules
24V dc
Input
2ĆWire Transmitter
RTP4
Output
Input
Return
24V dc
Input
Output
Input
Return
24V dc
4ĆWire Transmitter
24V dc
Input
2ĆWire Transmitter
Output
Input
Return
24V dc
Module supplies loop power
User supplies loop power
User supplies loop power
with 4Ćwire transmitter
i
i
i
(sourcing)
(sinking)
(sinking)
Inputs can be configured as sourcing or sinking inputs. For sourcing
inputs, the N-series module supplies the loop power. For sinking
inputs, you supply the loop power.
When the loop power is supplied externally, the 16-bit resolution
provides 65535 counts over the 0–20mA current range. This
provides about twice the resolution of voltage inputs with external
resistors.
Sourcing Input Analog
Modules