TM 5-3895-374-24-1
Chapter 6
Wiring Your I/O Modules
Contact Output Circuits - AC or DC
Relays can be used for either AC or DC output circuits and accommodate
either sinking or sourcing field devices. These capabilities are a result of the
output switch being a mechanical contact closure, not sensitive to current flow
direction and capable of accommodating a broad range of voltages.
This high degree of application flexibility makes contact output modules very
popular and useful in control environments with a broad mix of electrical I/O
circuit requirements.
Solid-State DC I/O Circuits
The design of DC field devices typically requires that they be used In a specific
sinking or sourcing circuit depending on the internal circuitry of the device DC
input and output field circuits are commonly used with field devices that have
some form of internal solid state circuitry that need a DC signal voltage to
function.
Sourcing Device with Sinking Input Module Circuit
The field device is on the positive side of the power supply between the supply
and the input terminal When the field device Is activated, it sources current to
the input circuit.
(page 3-418
