Rockwell Automation 1769-OF4VI Compact I/O Isolated Analog Modules - Manual (Page 27)

Publication 1769-UM014B-EN-P - May 2010
Installation and Wiring 2-11
1769-IF4I Input Module Guidelines
 If multiple power supplies are used with analog inputs, the power supply
commons must be kept at potentials that do not result in the module’s
working voltage rating being exceeded.
 The 1769-IF4I module does not provide loop power for analog inputs.
Use power supplies that match the input transmitter specifications.
 Differential analog inputs are more immune to noise than single-ended
analog inputs.
 Voltages on Ch+, Ch-, and Ch_IRtn for a single, isolated channel of the
1769-IF4I module must not exceed the module’s maximum overload
levels.
 1769-IF4I channels used as current inputs require a jumper to be placed
between a channel’s CH_IRtn and Ch- terminals.
1769-OF4CI and -OF4VI Output Modules Guidelines
 Voltage outputs (Vout 0+ to Vout 3+ for 1769-OF4VI) of the output
module are referenced to each channel’s Vout- terminal (channels are
isolated from each other). Load resistance for a voltage output channel
must be equal to or greater than 2 k.
 Current outputs (Iout 0+ to Iout 3+ for 1769-OF4CI) of the output
module source current that returns to each channel’s Iout- terminal
(channels are isolated from each other). Load resistance for a current
output channel must remain between 0 and 500 .
Effect of Transducer/Sensor and Cable Length Impedance on Voltage Input
Accuracy
For voltage inputs, the length of the cable used between the transducer/sensor
and the 1769-IF4I module can affect the accuracy of the data provided by the
module.
Figure 2.4 Voltage Input Accuracy
V in
Vs
Ri
Rc
Rc Rs
+
-