Triconex Trident, Planning And Installation Manual

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Input/Output Modules 69
Chapter 3 System Description
Analog Output Modules
The following analog output components are available.
Analog Output (AO) Modules contain the circuitry for three identical, isolated
channels. Each channel includes a proprietary ASIC that receives its output table
from the I
⁄
O communication processor on its corresponding main processor. The
AO Modules use special shunt circuitry to vote on the individual output signals
before they are applied to the load. This voter circuitry insures only one output, A
or B or C, is driving the field load. The shunt output circuitry provides multiple
redundancy for all critical signal paths, guaranteeing safety and maximum
availability.
The AO Modules continuously execute forced-switch diagnostics (FSD) on each
point. By carefully forcing error conditions and observing proper behavior of the
voting circuitry, high reliability and safe operation is insured. This safety feature
allows unrestricted operation under a variety of multiple-fault scenarios.
The AO Modules support hot sparing for online replacement of a faulty module or
continuous back-up to an active module. The AO Modules are mechanically keyed
to prevent improper installation in a configured baseplate.
Model Description Current Type
3481 Analog Output Module 4 @ 4–20 mA Commoned
3482High-Current Analog Output Module 2 @ 4–2 0 mA,
2 @ 4–40 mA
Commoned,
High Current
2481 Analog Output Baseplate Direct
Termination