Manual 26166V1 MicroNet Simplex & MicroNet Plus
Woodward 86
Chapter 8.
Discrete I/O Modules
8.1—Introduction
There are five types of discrete I/O modules currently available with the MicroNet system. These include
two types of 48/24 Discrete Combo module (48 discrete inputs, 24 discrete outputs), 48Ch DI module,
32Ch DO module, and the 64Ch DO module.
Discrete I/O field wiring requirement are detailed in Chapters 13 and 15.
Unshielded field I/O cables may only be used inside the cabinet or for cabling that is restricted to very
short distances near the cabinet. Also short, on engine, sections of Discrete Input (DI) & Output (DO)
wires/cabling may be used from the engine junction box were they are restricted to be on the
engine/turbine. In addition, coil or wetting voltage commons, as applicable, must be routed with the field
I/O wire bundles inside the shielding. Shielding may be electrically continuous metal conduit, cable armor,
or completely enclosed metal cable ways, as well as shielded cable, as long as the items listed are
grounded only to the cabinet housing the MicroNet system and are electrically continuous between the
field termination and cabinet.
Routing coil and wetting voltage common wires with signal wires and shielding of DI/DO field wires are
required due to the possibility of large transients from load dump of high-current inductive loads and
indirect lightning strike currents flowing in Protective Earth (PE) ground. If wires are routed separately
from commons and are not shielded, transients that are large enough will be coupled into the input or
output wiring and cause state changes to the signals for a short time.
Figure 8-1. DI/DO Field Wire Shielding Example (Non-Marine)
8.2—MicroNet Discrete I/O Smart-Plus Module (HDDIO)
8.2.1—Module Description
The HDDIO module is a MicroNet Plus module that will allow the customer to access information about
the module during operation via AppManager.
A 48/24 Discrete Combo module contains circuitry for forty-eight optically isolated discrete inputs and
twenty-four discrete outputs. These modules require no calibration; a module may be replaced with
another module of the same part number without any adjustment. There are two different FTM I/O
configurations for the MicroNet Discrete I/O Smart-Plus Module.
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