Metso IOP331 16-Channel 48 VDC Common Input Module

Metso IOP331 16-Channel 48 VDC Common Input Module

  • Model: IOP331
  • Manufacturer: Metso Automation / MAX Controls
  • System: maxPAC I/O / maxDNA distributed control architecture
  • Product Type: Digital Input Module
  • Core Function: Acquires 48 VDC discrete field signals and transfers the input status to the maxPAC I/O bus and associated DPU.
  • Channel Count: 16 digital inputs
  • Input Configuration: Common input
  • Nominal Input Voltage: 48 VDC
  • Input Current: 5 mA per point at 48 V
  • On-State Voltage: 22 V
  • Isolation: 250 VAC continuous; 1,500 VAC for 1 minute, user input to logic
  • I/O Bus Address: One address
  • System Application: Metso maxPAC distributed I/O
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Category: SKU: Metso IOP331 16-Channel 48

Description

Metso Automation IOP331 48 VDC Digital Input Module

 

Key Technical Specifications

Parameter IOP331 Specification
Manufacturer Metso Automation / MAX Controls
Model IOP331
System maxPAC I/O
Module Type Digital Input
Input Type DC discrete
Nominal Input Voltage 48 VDC
Maximum Rated Input Voltage 60 VDC
Number of Channels 16
Input Configuration Common
Input Current 5 mA per point @ 48 V
On-State Voltage 22 V
Input Range Approximately 40–150% of rated voltage
Field-to-Logic Isolation 250 VAC continuous
Isolation Test Rating 1,500 VAC for 1 minute
I/O Bus Address One address
Input Power from 24 V System Supply 50 mA
Channel Indicators Individual input-status LEDs
Module Status Active / communication indication
Loop Power Status Fuse-disconnect indication

The maxPAC reference states that the IOP331 uses 16 common digital inputs. Its input circuitry includes signal conditioning, current limiting, an input threshold, optical isolation, and buffering/latching before the data is presented to the I/O bus as a 16-bit word.

 

Product Introduction

The Metso Automation IOP331 is a 16-channel, 48 VDC common digital input module for the maxPAC I/O subsystem. It is intended for discrete field signals such as status contacts, interlocks, switches, and other 48 VDC on/off signals used in distributed control applications.

Each input has front-panel status indication, while the module communicates with the DPU through the maxPAC I/O bus. Field input circuits are isolated from the logic circuitry, and the module uses a front-accessible fuse disconnect for the loop-power supply.

IOP331

Applications & Field Pitfalls — Engineer’s Perspective

IOP331 is a legacy maxPAC component, so the primary replacement concern is matching the original field-voltage architecture, not simply finding another 16-channel digital input card. The distinction between is critical: IOP330 is the 24 VDC common-input version, while is designed for 48 VDC common inputs.

Typical Application Areas

  • 48 VDC discrete monitoring — status and permissive signals within industrial control systems.
  • Motor and equipment status — monitoring contact-based running, fault, trip, or auxiliary signals.
  • Process interlocks — acquisition of discrete permissive and shutdown-related signals.
  • Legacy maxPAC DCS installations — direct replacement of an existing where the original rack and DPU architecture remain in service.

Field Pitfalls

  1. Do not substitute IOP330 without checking the field voltage. IOP330 is rated for 24 VDC, whereas is the 48 VDC version.
  2. “Common input” matters. is not the channel-to-channel isolated equivalent of the IOP334. The common-input architecture affects field wiring and grounding arrangements.
  3. Check the loop-power circuit. The 48 V field-power signals are routed to the channels through a fuse disconnect accessible from the front of the module.
  4. Check redundant configurations carefully. The maxPAC documentation provides specific wiring arrangements for redundant common-DI modules. Do not assume a redundant installation can be rewired without checking the original cabinet drawings.
  5. Verify the I/O bus address. The module requires one I/O bus address; incorrect addressing can make a physically correct replacement appear defective.

 

Related Products

  • IOP330 — 24 VDC common-input, 16-channel digital input module. It is the closest functional counterpart to , but the field voltage is different.
  • IOP334 — 24 VDC isolated digital input module with 16 isolated channels; different field isolation architecture.
  • IOP332 — 120 VAC/DC isolated digital input module with 16 channels.
  • IOP333 — 240 VAC/DC isolated digital input module with 16 channels.
  • IOP350 — Form C relay output module with 10 channels; output rather than input function.
  • IOP351 — Form A/B relay output module with 16 channels.
  • IOP320 — 4–20 mA analog output module with 8 channels.
  • IOP302 — 4–20 mA common-input analog module with 16 channels.
  • IOP371 — Optical Bus Extender used for maxPAC I/O bus extension.
  • IOP382 — 8-slot PAC rack hardware for the maxPAC I/O architecture.

 

Procurement Note

For a replacement request, specify:

Metso Automation — 48 VDC Common Input — 16 Channels — maxPAC I/O

The most important verification points are the model marking, 48 VDC field supply, common-input wiring, rack position, and I/O bus address. Do not substitute an IOP330 or IOP334 simply because the modules have a similar channel count.

The maxPAC documentation also identifies the input as accepting a high-level signal from approximately 40% to 150% of its rated voltage, with 5 mA nominal input current and a 22 V on-state threshold.

For an installed legacy system, a clear photograph of the module label and the associated field connector is useful when verifying whether the replacement should be or another maxPAC digital-input variant.

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