Rockwell Automation T3420AF ICS Regent Analog Input Modules - Manual (Page 8)

Analog Input Modules (T3420A, AF)
8
Industrial Control Services
Input Over Voltage Protection
All analog inputs, regardless of mode and analog references
(AREF1 and AREF2), are protected from over-voltages (these
ranges are shown on page 37).
Current Measurement Considerations
Precision resistors external to the module are required to
convert currents to voltages that can be measured directly by
the module. The resistors can be mounted on field marshaling
terminals or are provided using the appropriate analog input
termination blocks. For differential current measurements,
both sides of the external resistor are brought onto the
module.
It is possible to mix current and voltage measurements on the
same module as long as they can work with the same voltage
range selected. In the case of single-ended measurements,
this either requires that both current and voltage
measurements are referenced to the same reference point
(AREF1 or AREF2), or that voltage inputs be on one set of
eight inputs and current inputs on the other set.
Input Range and Mode Selection Jumpers
The jumpers that determine the mode and input range for the
module are set at manufacturing time for an input range of 1
to 5 volts and the 16-channel, single-ended input mode. If
other input ranges or another mode is desired these jumpers
must be repositioned to the appropriate settings.
There are 17 jumper locations that are used. They are
summarized in Tables 2 and 3, below. The module’s cover
must be removed to access and reposition the jumpers.