Mitsubishi FX2N-4AD-PT — 4-Channel PT100 RTD Temperature Input Module for FX2N / FX3U PLCs | Genuine New

Before specifying this module, there's one thing worth clarifying upfront: the FX2N-4AD-PT is not a general-purpose analog input module. It does one specific job — reading PT100 platinum resistance thermometers (RTDs) — and it does that job very well. If your application involves temperature measurement with PT100 sensors and you're running an FX2N or FX3U system, this is exactly the module you need. If you're looking for voltage or current analog inputs (0–10V, 4–20mA), that's a different product entirely — the FX2N-4AD.

The distinction matters because the two modules are occasionally confused in procurement. The catalog suffix tells you everything: "PT" = PT100 temperature input. The FX2N-4AD-PT provides 4 independent PT100 RTD input channels, measuring temperatures from –200°C to +600°C with 12-bit resolution, connecting directly to the FX2N or FX3U extension bus without any external signal conditioning or transmitters.

✅ Genuine Mitsubishi Electric. New original factory sealed. One-year warranty. In stock — ships worldwide.

Why PT100 Rather Than a Thermocouple Module?

Engineers choosing between PT100 (RTD) and thermocouple temperature measurement often face this question at the sensor selection stage. The FX2N-4AD-PT is purpose-built for PT100 RTDs, which have characteristics that make them preferable in certain situations:

PT100 sensors deliver higher accuracy and better repeatability than most thermocouple types — typically ±0.1°C at the sensor versus ±1–2°C for Type K thermocouples. They don't require cold-junction compensation, which removes a source of measurement drift common in thermocouple systems. The downside is a narrower temperature range (–200 to +600°C for PT100, versus up to 1200°C+ for some thermocouples) and slightly higher sensor cost.

For applications in food processing, pharmaceutical manufacturing, HVAC, and industrial ovens operating below 600°C, PT100 is often the more accurate and stable choice. The FX2N-4AD-PT directly interfaces with standard 3-wire PT100 sensors and handles the linearization internally — the PLC program receives a digital value in BFM (buffer memory) that directly represents the temperature in 0.1°C increments.

⚙️ Technical Specifications

Parameter	Specification
Manufacturer	Mitsubishi Electric
Catalog Number	FX2N-4AD-PT
Module Type	Special function module — PT100 RTD temperature input
Input Channels	4 (independent, all channels active simultaneously)
Sensor Type	PT100 platinum resistance thermometer (RTD) only
Wiring	3-wire PT100 connection (lead resistance compensation)
Measurement Range	–200°C to +600°C
Resolution	12-bit → 0.1°C per digit
Accuracy	±1°C or better (within specified operating range)
Conversion Speed	~15ms per channel (60ms for all 4 channels)
BFM Address	BFM #0–#3: Channel 1–4 temperature data (×10, in 0.1°C units)
Extension Bus	Direct right-side bus connection to FX2N / FX3U
Power Consumption	5VDC from extension bus, 30mA
Compatible PLCs	FX2N, FX2NC (adapter required), FX3U, FX3UC (adapter required)
Operating Temperature	0°C to +55°C
DIN Rail Mounting	35mm standard
Condition	Genuine New / Factory Sealed

Reading Data from the FX2N-4AD-PT in Your PLC Program

The FX2N-4AD-PT is a special function module — unlike standard I/O extension modules, its data is not automatically mapped to X/Y addresses. Temperature readings are stored in the module's buffer memory (BFM) and must be read using the FROM instruction in the FX2N ladder program (or the equivalent in GX Works2/3).

Here's the practical programming approach:

Step 1 — Identify the module's unit number. Special function modules are numbered from the leftmost position as Unit 0, 1, 2... The FROM instruction requires this unit number.

Step 2 — Read channel data using FROM. Each channel's temperature is stored in a dedicated BFM register:

BFM #0 → Channel 1 temperature (value in 0.1°C — so 245 = 24.5°C)
BFM #1 → Channel 2 temperature
BFM #2 → Channel 3 temperature
BFM #3 → Channel 4 temperature

A typical FROM instruction to read Channel 1 into data register D10:

FROM K0 K0 D10 K1
│ │ │ └── Read 1 word
│ │ └─────── Store in D10
│ └─────────── Start from BFM #0 (CH1)
└─────────────── Unit number 0 (first special function module)

Step 3 — Scale the value. The raw BFM value is in 0.1°C units. To display 24.5°C, D10 will hold the value 245. Divide by 10 for display on an HMI, or work with the raw 0.1°C value in your control logic for finer resolution.

Step 4 — Check error flags. BFM #29 contains error status bits. A value of H0000 (all zeros) indicates normal operation. Non-zero bits indicate sensor open-circuit, over-range, or module fault conditions.

🆚 Choosing the Right FX2N Analog / Temperature Module

Plenty of engineers have ordered the wrong module because the naming looks similar. Here's a quick reference to avoid that mistake:

Module	Input Type	Sensor / Signal	Range	Use When...
FX2N-4AD-PT ← This unit	Temperature (RTD)	PT100 only	–200 to +600°C	You have PT100 RTD sensors wired in
FX2N-4AD-TC	Temperature (thermocouple)	Type K / J thermocouple	–100 to +1200°C	You have thermocouple sensors
FX2N-4AD	Analog voltage/current	0–10V, 0–20mA, 4–20mA	12-bit ADC	You need voltage or current analog inputs
FX2N-2AD	Analog voltage/current	0–10V, 4–20mA	2 channels	Lower channel count analog input
FX2N-4DA	Analog output	0–10V, 4–20mA	12-bit DAC	You need analog outputs (not inputs)

The most common ordering mistake: specifying FX2N-4AD when the application actually uses PT100 sensors (and vice versa). Always match the module suffix to the sensor type on your drawing before purchasing.

🏭 Where the FX2N-4AD-PT Gets Used

Food processing and cold chain — monitoring oven temperatures, blast chiller zones, and fermentation vessel temperatures where PT100's accuracy advantage over thermocouples directly impacts product quality and regulatory compliance.

Pharmaceutical manufacturing — cleanroom temperature mapping, autoclave cycle monitoring, and API synthesis reactor temperature feedback where ±1°C measurement accuracy is a process validation requirement.

HVAC and building management — chiller plant supply/return temperature differential measurement, air handling unit coil temperature monitoring, and underfloor heating zone control using standard PT100 duct and immersion sensors.

Plastic injection molding — mold temperature zone monitoring (separate from the mold temperature controller's own sensors) providing independent temperature data to the FX2N PLC for alarm and process logging.

Laboratory and test equipment — environmental chamber control, material testing furnace feedback, and calibration bath temperature monitoring where PT100 accuracy and stability are preferred over thermocouple drift.

Industrial boiler and heat exchanger control — feedwater temperature measurement, economizer performance monitoring, and condensate return temperature logging on process heating systems.

📦 Procurement & Stock Information

🔒 Genuine Mitsubishi Electric — not refurbished, not compatible replacement, not third-party
✅ New original — factory sealed with Mitsubishi Electric packaging and labels
📋 One-year warranty
📦 Original Mitsubishi factory box, securely packed for international transit
🌍 Worldwide express shipping (DHL / FedEx / UPS)
⚡ In stock — dispatches within 1–2 business days

❓ FAQ — Mitsubishi FX2N-4AD-PT PT100 Temperature Input Module

Q1: What's the difference between FX2N-4AD-PT and FX2N-4AD — can I use them interchangeably? No, they are completely different modules for different sensor types and cannot substitute for each other. The FX2N-4AD-PT reads PT100 RTD temperature sensors only — it expects the resistance change of a platinum element as its input signal. The FX2N-4AD is a general-purpose analog input module that reads voltage (0–10V, ±10V) and current (0–20mA, 4–20mA) signals from transmitters and other analog devices. Connecting a PT100 sensor to an FX2N-4AD will not produce temperature readings. Connecting a 4–20mA transmitter to an FX2N-4AD-PT will likely damage the module. Always match the module to the sensor type in your wiring design.

Q2: Does the FX2N-4AD-PT work with FX3U PLCs, or is it FX2N-only? The FX2N-4AD-PT is mechanically and electrically compatible with the FX3U extension bus and can be connected directly to the right side of an FX3U base unit alongside FX3U-native special function modules. The FROM/TO instructions for reading BFM data work identically on the FX3U. For FX2NC and FX3UC compact-format base units, a bus conversion adapter (FX2NC-CNV-IF or similar) is required due to the different connector format on those units. The FX2N-4AD-PT is not compatible with older FX0N, FX1S, or FX1N systems, which have a different extension architecture.

Q3: The module accepts "3-wire PT100" — what does the third wire do and can I use 2-wire sensors? The third wire in a 3-wire PT100 connection is used for lead resistance compensation. PT100 sensors measure resistance, and the resistance of the wires connecting the sensor to the module introduces a small but measurable error — typically 0.4Ω per meter of copper wire, which equates to roughly 1°C of measurement error per meter of wire length each way. The 3-wire connection allows the module to measure the lead resistance of one wire and subtract twice that value from the total measured resistance, effectively canceling the lead resistance error. You can connect 2-wire PT100 sensors by shorting the two negative (B) terminals together, but you lose lead resistance compensation and will have a fixed offset error proportional to wire length. For accurate measurements over any significant cable run, 3-wire PT100 sensors are strongly recommended.

Q4: How do I read the temperature value in my GX Works2 ladder program? Use the FROM instruction to read BFM (buffer memory) data from the module. The basic syntax is FROM [unit number] [BFM start address] [destination register] [number of words]. Temperature data is stored in BFM #0 (Channel 1) through BFM #3 (Channel 4), with each value representing temperature in 0.1°C units as a signed 16-bit integer. So a BFM value of 253 means 25.3°C, and –150 means –15.0°C. The unit number is determined by the module's physical position on the extension bus — the first special function module from the left is Unit 0, the second is Unit 1, and so on. Standard I/O extension modules (like FX2N-16EX, FX2N-16EYR) do not count as special function modules for unit numbering purposes.

Q5: One channel is reading an obviously wrong temperature — how do I diagnose it? Start by reading BFM #29 using a FROM instruction or the GX Works2 device monitor — this is the module's error status register. Each bit corresponds to a specific error condition: bit 0 = Channel 1 error, bit 1 = Channel 2 error, etc. A set bit indicates that channel has detected a fault, most commonly an open-circuit sensor (disconnected or broken PT100 wire) or an out-of-range reading (temperature outside –200 to +600°C, which can indicate a wrong sensor type or wiring fault). If the error bit is clear but the reading is still incorrect, check: (1) correct 3-wire connection at the module terminals; (2) PT100 sensor resistance at room temperature — a genuine PT100 should measure approximately 100Ω at 0°C and about 109Ω at 23°C; (3) that the sensor is actually a PT100 and not a PT1000 or Ni100 (different resistance curves, incompatible with this module).

Q6: Is the FX2N-4AD-PT still available new, or has it been discontinued by Mitsubishi? The FX2N product family is a mature product line — Mitsubishi Electric has progressively migrated to FX5U as the current-generation platform. However, FX2N-4AD-PT units continue to be available as new original stock through authorized and specialist distributors, as there remains significant installed base of FX2N and FX3U systems in production worldwide. This unit ships as new original factory sealed stock. For new machine designs, engineers should evaluate whether the FX3U-4AD-PT-ADP (the FX3U-native PT100 adapter block) would be more appropriate, as it supports newer GX Works3 features. For replacement and maintenance of existing FX2N or FX3U systems, the FX2N-4AD-PT remains the correct and direct replacement part.

Q7: How many FX2N-4AD-PT modules can I connect to a single FX2N base unit? The FX2N system supports up to 8 special function modules per system, and each FX2N-4AD-PT counts as one special function module. With 4 input channels per module, a fully expanded system could theoretically monitor up to 32 PT100 sensors from a single FX2N CPU — though in practice, the total I/O point budget (maximum 256 points across all extension devices) and the extension bus power budget also apply. Each FX2N-4AD-PT draws 30mA from the 5VDC extension bus. Check your FX2N base unit's extension power specifications against the total current draw of all connected extension modules before commissioning a fully loaded system.

FX2N-4AD-PT Genuine Mitsubishi FX2N4ADPT PLC Analog Module