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Phone: +86 16626708626Description
Key Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | IOP304 |
| Alternate Part Number | 181503 |
| Manufacturer | Valmet Metso Automation |
| Module Type | Input Module / PLC Module |
| Primary Function | Isolated analog input for TC/Mv signals |
| Signal Type | Thermocouple (TC) / Millivolt (Mv) input |
| Known Revisions | Rev C1/D2, Rev E2/F |
| Supply Voltage | 120V AC/DC (per Rev C1/D2 listing) |
| Category | Input / Output Modules |
| System Compatibility | Metso DNA-compatible automation system |
| Condition | New and used available |
| Availability | Limited stock, surplus market |
Product Introduction
Valmet IOP304 is an isolated analog input module (part number 181503) used in Metso DNA automation systems for thermocouple and millivolt signal acquisition. It provides isolated input channels for temperature and process monitoring in industrial control racks.
This module is typically sourced as new surplus or used from decommissioned Metso/Valmet systems, since it is an obsolete legacy part. Market listings show multiple revisions (C1/D2 and E2/F), so match the revision on your installed unit before ordering.
- IOP304
Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to this Part | Quick Check Method | Recommendation |
|---|---|---|---|---|
| No input reading on channel(s) | Module power failure or sensor fault | ✅ High | Measure module supply voltage (check 120V AC/DC input), verify sensor wiring | Replace module if input power is present but no reading |
| One channel dead, others work | Channel input circuit failure | ✅ High | Test affected channel with known good sensor, compare to working channel | Replace module if single channel fails consistently |
| All channels show 0 or open | Power supply or backplane fault | ❌ Medium | Check 120V supply at module terminals, verify backplane power | Check PSU and backplane before replacing module |
| Input reading drifts or fluctuates | Sensor wiring noise or grounding issue | ❌ Low | Check sensor cable shielding, verify single-ended ground, inspect for loose terminals | Fix wiring/grounding before replacing module |
| Erroneous high/low reading (open loop) | Sensor disconnected or thermocouple broken | ❌ Medium | Verify sensor continuity with multimeter, check for open circuit | Replace sensor first, then module if reading still wrong |
| Module LED off or error | Module fault or supply voltage missing | ✅ High | Measure 120V AC/DC at input terminals, check module status LED | Check PSU and fuses before replacing IOP304 |
| Communication error with controller | Backplane bus or configuration mismatch | ❌ Medium | Check PLC diagnostic buffer, verify module address and revision | Verify rack configuration before replacing module |
Contact technical support with photos of the front label, revision tag, input wiring, multimeter readings (supply voltage and sensor continuity), and PLC diagnostic log if you cannot isolate the fault.
Frequently Asked Questions
Q: Is Valmet IOP304 still available from the factory?A: No. It is an obsolete legacy input module. You will find it only through surplus dealers as new surplus or used stock from decommissioned Metso/Valmet systems.
Q: What does “IOP304” stand for?A: IOP means Input/Output Module. The 304 indicates this is the isolated analog input variant for thermocouple (TC) and millivolt (Mv) signals in Metso DNA systems.
Q: I see Rev C1/D2 and E2/F listed—are they interchangeable?A: Do not assume they are interchangeable. The revision matters for firmware compatibility and signal calibration. Match the revision on your installed unit before ordering.equipt+1
Q: Can I hot-swap this input module?A: Do not assume it is hot-swappable. Kill power to the rack before removal. Pulling I/O modules live can damage the backplane or cause input channel faults.
Q: Will configuration be lost when I swap it?A: The module itself does not hold the PLC program. Your controller retains the logic, but you should verify the module address, channel mapping, and calibration settings after the swap.
Q: What signal types does IOP304 accept?A: It accepts thermocouple (TC) and millivolt (Mv) input signals, which are commonly used for temperature monitoring with thermocouple sensors in industrialprocess applications.
Q: What is the supply voltage for this module?A: Per the Rev C1/D2 listing, it operates on 120V AC/DC. Verify the supply voltage in your rack before installing a replacement.rivercityindustrial
Q: Why is it cheaper than ordering new from OEM?A: Because the OEM does not actively stock it. You are buying surplus from decommissioned systems or excess inventory, which drives the price down but adds verification responsibilities for revision and condition.
Q: Is this a direct replacement for every IOP304?A: The model number is the right first check. However, you must match the revision (C1/D2 or E2/F) and verify your Metso DNA rack and controller firmware are compatible. Do not assume plug-and-play without that check.
