Wiring IFM PN3004 Pressure Sensor to Siemens LOGO! 8 24V AI

Overview

Connecting an IFM PN3004 pressure sensor to a Siemens LOGO! 8 24V base module is a routine integration when the panel is designed for a 0-10 V analog signal. The base LOGO! 8 24VCE provides two dedicated analog inputs (AI1 on I7 and AI2 on I8) that accept 0-10 V DC without any external signal conditioner. The IFM PN3004 belongs to the PN3 family of 4-pin M12 pressure transmitters and exposes a 0-10 V single-ended output on Pin 2 of the M12 connector, which lands directly on I7. The wiring is the only piece that trips installers up: a 0-10 V signal is single-ended and the sensor's 0 V return (Pin 3, blue) MUST share the LOGO! 24 V supply negative terminal (M). Connecting only the L+ signal wire (Pin 2) without the L- return leaves the analog input stage with no reference, so the LOGO! reads 0 or a floating value.

This reference covers the exact pinout, the polarity decision, the LOGO! Soft Comfort configuration, scaling math, power-supply rules, troubleshooting, and the verification sequence. It also covers the optional use of Pin 4 (the PN3004 switching output) and how to convert to a 4-20 mA PN variant using a 250 Ω resistor on the LOGO! AI input.

LOGO! 8 24V Base Module: AI Channel Identification

The LOGO! 8 24V base module (the 24VCE, 24VCEO, 24VCEo, and equivalent OBAx variants) ships with eight digital inputs on the base. Inputs I7 and I8 are dual-function: by default they are digital inputs, but when AI1/AI2 is enabled in the LOGO! Soft Comfort project properties, the same two terminals operate as 0-10 V analog inputs. No physical jumper, no module change, no firmware patch is required. The LOGO! automatically routes the I7/I8 voltage tracks to the internal 10-bit ADC when the AI is enabled.

The catalog suffix -0BAx is the firmware generation (OBA0, OBA1, OBA2, OBA6, OBA7, OBA8, etc.). The AI behavior is the same across the family; the differences are in the Ethernet/Web server feature set and the LOGO! Soft Comfort library version. Always use the Soft Comfort version that matches the -0BAx generation installed in the base module - download the matching firmware from the Siemens LOGO! Web-Based Automation portal before commissioning.

Key electrical limits of the AI input on the 24 V base module:

• Input range: 0-10 V DC (no negative range; signal below 0 V reads as 0).
• Absolute maximum continuous input voltage: 30 V DC.
• Input impedance: typically 100 kΩ to the M terminal.
• Cable length without shielded twisted pair: keep under 10 m for clean readings; up to 30 m is acceptable with shielded cable bonded to PE at one end.

IFM PN3004 Pressure Sensor Specifications

The IFM PN3004 belongs to the PN3 series of compact pressure transmitters with a 4-pin M12 connector. The PN3 family shares a consistent pinout but varies by pressure range and output type (0-10 V, 4-20 mA, IO-Link, or dual output). Always cross-check the specific PN3004 variant's pressure range, output type, and supply voltage against the IFM datasheet before wiring; the part-number suffix encodes these parameters.

The pressure range (0-1 bar, 0-10 bar, 0-25 bar, 0-50 bar, 0-100 bar, etc.) is encoded in the variant suffix. The wiring shown below is independent of the pressure range and works for any PN3 sensor with a 0-10 V output. For a 4-20 mA PN variant, the same PN3 connector applies, but the 0-10 V input of the LOGO! 8 needs a 250 Ω precision resistor across I7 and M to convert the current to a 1-5 V signal; see the section below for the conversion math.

M12 Connector Pinout Standard (IFM PN3 Series)

The IFM PN3 family uses a 4-pin M12 A-coded connector. The pin-to-color convention follows the IEC 60947-5-2 standard and is consistent across the PN3 line, including the PN3004. The correct pinout is:

1. Pin 1 (BN, brown): +24 V DC supply - this is the sensor's L+.
2. Pin 2 (WH, white): Analog output - for the 0-10 V variant, this is the 0-10 V signal. For a 4-20 mA variant, this is the current loop positive.
3. Pin 3 (BU, blue): 0 V DC supply - this is the sensor's L- / M. It is also the reference for the 0-10 V signal.
4. Pin 4 (BK, black): Switching output - PNP or NPN depending on the variant configuration. Not used in the 0-10 V analog path.

A common confusion in field installations is to label the blue wire as Pin 4 (it is in fact Pin 3) or to assume Pin 4 is the 0 V return (it is the digital switching output). Always read the connector, do not trust the wire label on a previous install - the IFM standard is fixed: brown=24V, white=signal, blue=0V, black=digital out.

Wiring the PN3004 to LOGO! 8 I7 (AI1)

The signal path is a 3-wire connection: 24V+ to the sensor, 0V return shared between the LOGO! 24V supply and the sensor, and the analog signal on Pin 2 (white) back to I7. Pin 4 (black, switching output) is left disconnected for the analog-only application.

To answer the original polarity question explicitly: no, connecting only Pin 2 (white, the L+ signal) to I7 is NOT correct on a single-ended 0-10 V input. The sensor's 0 V return on Pin 3 (blue) must also be landed on the LOGO! M terminal so that the I7 input stage has a defined 0 V reference. If the return is missing or lands on a separate floating 0 V rail, the AI1 reading will be 0, unstable, or pegged to full scale depending on the leakage path.

Wiring topology (inline SVG diagram)

Power-Supply and Common-Reference Rules

Both the LOGO! 8 24VCE base and the IFM PN3004 must share a common 0 V reference. A common installation error is to power the sensor from a separate 24 V DC supply while the LOGO! 8 is powered from its own 24 V source: the analog ground then floats relative to the LOGO! 0 V and the AI reading will be unstable, clipped, or zero. The wiring rules below are the only safe way to bring a 0-10 V sensor onto a LOGO! 8 base.

1. Use a single 24 V DC power supply for both the LOGO! 8 and the PN3004. If the panel has a second 24 V rail, do NOT use it for the sensor - it will break the common-reference rule.
2. Bond the LOGO! M terminal to the supply 0 V at the same terminal block that feeds the LOGO! power input.
3. Land the PN3004 blue wire (Pin 3) on the same M terminal. This is the single most important wire in the install.
4. Keep the analog signal cable in a separate conduit or at least 100 mm from any VFD output cabling to avoid coupling common-mode noise into the 0-10 V loop.
5. If the cable run exceeds 10 m, use a shielded cable (e.g. LAPP EVC M12 sensor cable, shielded twisted pair) and bond the shield to PE at the panel end only - the field end stays floating to avoid a ground loop.
6. Verify the common-reference connection with a multimeter on continuity mode between PN3004 Pin 3 and the LOGO! M terminal before applying power.

LOGO! Soft Comfort Configuration

Configuring I7 and I8 as analog inputs requires three actions in LOGO! Soft Comfort: enable the AI in the hardware configuration, scale the 0-1000 raw value to engineering units, and route the scaled value to a display or threshold block. The step-by-step below applies to Soft Comfort V8.x and later; the menu text may vary slightly by Soft Comfort version.

1. Open the project in LOGO! Soft Comfort (V8.x or later for the OBA8 base; V8.4+ for the OBA2 base). Match the Soft Comfort version to the -0BAx generation of the connected LOGO! base.
2. In the menu, select File → Properties → Parameters → AI and set AI1 to "On" and AI2 to "On" as required. Without this step the program will treat I7 and I8 as digital inputs.
3. On the programming canvas, drag the Analog Input special function (from the special-functions catalog) or place a Message Text block and bind it to AI1. In the program the analog input is referenced as AI1 (I7) and AI2 (I8).
4. Insert an Analog Amplifier block to apply gain and offset. For a 0-10 V sensor mapped to a 0-1000 raw value: Sensor min = 0, Sensor max = 1000, Gain = 1, Offset = 0 for a direct read.
5. For an engineering unit (e.g. bar), use the Arithmetic block or a Math instruction:

   Pressure_bar = (AI1 / 1000) * Sensor_max_bar
   Example (sensor full scale = 10 bar): AI1 = 500 → 0.50 * 10 bar = 5.00 bar

6. For display on the LOGO! built-in screen or LOGO! TDE, route the scaled value into a Message Text block with the bar / psi / kPa suffix. Enable the bar-graph option to show the signal as a percentage of full scale.
7. Download the program to the LOGO! and watch the online view to confirm AI1 reads 0-30 raw at 0 bar and 950-1000 raw at full scale.

Scaling the Raw AI Value to Engineering Units

LOGO! 8 base module AI1/AI2 is a 10-bit converter over 0-10 V. The raw value is presented as 0-1000 (units of 10 mV). Resolution is approximately 9.8 mV per step, which on a 0-10 bar sensor yields ~9.8 mbar per step. This is more than adequate for the typical PN-series pressure switch application, but it is not laboratory-grade resolution. For higher resolution, use the LOGO! 8 AM2 RTD extension module (12-bit) or move to a LOGO! 8 with the OBA8 firmware (some variants expose 12-bit AI).

If the sensor's full-scale output is not 10 V (for example a 0-5 V variant, or a 1-5 V variant when driven by a current loop resistor), set the gain and offset in the Analog Amplifier so that a 1000 raw value corresponds to the sensor's full-scale pressure and a 0 raw value corresponds to the sensor's zero. For a 1-5 V sensor:

Gain = 1000 / (V_max - V_min) = 1000 / 4 = 250
Offset = -V_min * Gain = -1 * 250 = -250

Reading a Second Pressure Sensor on I8 (AI2)

If a second pressure sensor is needed (e.g. differential pressure across a filter, or a redundant pressure transmitter for safety indication), wire it the same way to I8. The second sensor is referenced as AI2 in the LOGO! program.

Both sensors share the same M terminal and the same L+ feed. The two AI inputs are sampled by the LOGO! base module independently; there is no cross-talk. If the application needs more than 2 analog inputs, add a LOGO! 8 AM2 module (2 AI, 12-bit) or an AM2 RTD module (2 AI for PT100/PT1000) on the right side bus.

Using a 4-20 mA PN Variant (Resistor Conversion)

The IFM PN3 series also includes 4-20 mA current-loop variants. The pinout is identical (Pin 2 = current output), but the LOGO! 8 base AI input is 0-10 V only. To read a 4-20 mA sensor on a 0-10 V base AI, install a precision 250 Ω resistor between I7 and M and convert the current to voltage.

To convert the 1-5 V range to 0-1000 in the LOGO! program, set the Analog Amplifier:

Sensor min raw: 100 (corresponds to 4 mA / 1 V / 0% of scale)
Sensor max raw: 500 (corresponds to 20 mA / 5 V / 100% of scale)
Gain = 1000 / (max - min) = 1000 / 400 = 2.5
Offset = -100 * 2.5 = -250

Use a 0.1% precision resistor (Vishay Z201 or equivalent) for the 250 Ω; a 1% carbon-film resistor will drift with temperature and introduce a 1-2% measurement error. Mount the resistor inside the panel near the LOGO! terminals, not at the sensor end, to keep the current loop short and noise-free.

Troubleshooting Matrix

Verification Procedure

1. Power the LOGO! 8 24VCE and confirm the green "OK" / RUN LED on the base is steady (not flashing red or amber).
2. Apply 24 V to the PN3004 and confirm the sensor status LED is green (not red, not flashing). A red LED on a PN3 sensor typically means overpressure, broken element, or supply undervoltage.
3. In LOGO! Soft Comfort, place a Message Text block on AI1 with a numeric display and download to the LOGO! base.
4. Read the raw value with no pressure applied. A correctly wired 0-10 V sensor at zero pressure should return a raw value of 0-30 (small zero offset is normal; consult the PN3004 datasheet for the published zero tolerance).
5. Apply a known pressure with a dead-weight tester or a calibrated reference gauge. Verify the scaled value matches within the sensor's published accuracy spec (typically ±0.5% of full scale for the PN3 family).
6. Verify a step change: apply 50% of full-scale pressure, read back, then release. The AI value should track within 2-3 LSB of the expected value within the sensor response time (typically < 2 ms for the PN3 ceramic cell).
7. Cycle power to confirm cold-start behavior is consistent - no need to re-calibrate after a power cycle.
8. Document the zero pressure reading, the full-scale reading, the supply voltage, and the sensor serial number in the commissioning log. This becomes the baseline for trending and predictive maintenance.

Pin 4 (BK) of the PN3004 - Optional Switching Output

Pin 4 (black) on the IFM PN3004 is a switching (digital) output. The default configuration is a PNP output that closes at a configurable setpoint. The setpoint is adjusted via the teach-in button on the sensor body, by IO-Link (if supported by the variant), or by the IFM LineVision configurator. If a digital trip is needed in addition to the 0-10 V reading, route Pin 4 to a normal LOGO! digital input (e.g. I1-I6) and use it as a setpoint alarm or for interlocks. For analog-only applications, leave Pin 4 disconnected and insulate the wire with heat-shrink to prevent a short to chassis or to the signal wire.

Extension Modules and AM2 Considerations

The two base analog inputs are often enough for a single-pressure-loop control, but the LOGO! 8 bus supports up to 24 digital inputs, 20 digital outputs, 8 analog inputs, and 8 analog outputs when fully expanded. For applications that need more analog channels, use the AM2 or AM2 RTD extension modules on the right-side bus.

The AM2 extension module uses the same 0-10 V input type as the base, with 12-bit resolution (0-1000 raw value, same scaling math). It draws its supply from the LOGO! bus, so the M terminal is internally common with the base module - no extra wiring is required for the 0 V reference. This makes adding a second pressure sensor, a flow sensor, or a level sensor a matter of clicking the AM2 onto the bus and wiring the M12 connector.

Sample LOGO! Soft Comfort Program

| Block B001: Message Text (display)              |
|   Reference: AM1 (scaled pressure)              |
|   Display: "Pressure: %d.%d bar"                |
|   Bar graph: AM1 / 1000 (0-1000 = 0-100% bar)   |
|   Trigger: always on                            |

| Block B042: Analog Amplifier (AI1)              |
|   Sensor type    : 0 - 10 V                     |
|   Min raw        : 0                            |
|   Max raw        : 1000                         |
|   Gain           : 1.0                          |
|   Offset         : 0                            |
|   → AQ1 (raw value 0-1000)                |

| Block B043: Arithmetic (AQ1 → AM1)         |
|   Operator       : (x * a) + b                  |
|   a = 0.01  (10 bar full scale example)         |
|   b = 0.0                                       |
|   → AM1 (engineering units, bar)          |

| Block B007: Analog Threshold Trigger (AM1)      |
|   On threshold    : 8.00 bar (high alarm)       |
|   Off threshold   : 7.50 bar (hysteresis)       |
|   → Q1 (pump shutoff)                    |

| Block B007: Analog Threshold Trigger (AM1)      |
|   On threshold    : 0.50 bar (low alarm)        |
|   Off threshold   : 0.80 bar (hysteresis)       |
|   → Q2 (low-pressure indicator)          |

This minimal program reads the IFM PN3004 on AI1, scales it to bar in the engineering range, displays the value with a bar graph on the LOGO! TDE or built-in screen, and asserts two digital outputs for high-pressure pump shutoff and low-pressure indication. The two threshold triggers use independent hysteresis to avoid chattering on a noisy signal.

Commissioning Checklist

FAQ