E+H FMU42-APB2A22A Replacement for Prosonic S Series

Product Overview

E+H FMU42-APB2A22A Replacement for Prosonic S Series: Seamless Transition from Legacy Ultrasonic Level Systems

The Endress+Hauser FMU42-APB2A22A is a high-performance ultrasonic level transmitter from the Prosonic S series, engineered for non-contact continuous level measurement in liquids, pastes, and bulk solids. For facilities operating aging FMU40, FMU41, or FMU44 transmitters — or earlier Prosonic T FMU230/FMU231 units — the FMU42-APB2A22A delivers a direct upgrade path with minimal disruption to existing wiring infrastructure, control cabinet layouts, and PLC/DCS integration architectures.

This product page is designed to support procurement engineers, instrumentation technicians, and plant managers who are planning a controlled migration from discontinued or end-of-life Endress+Hauser ultrasonic level devices to the current Prosonic S platform. Whether you are replacing a single field instrument or executing a site-wide instrumentation upgrade, the FMU42-APB2A22A provides the compatibility, reliability, and documentation support required for a smooth cutover.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful migration from a legacy Prosonic T or early Prosonic S installation to the FMU42-APB2A22A typically involves more than a one-for-one transmitter swap. In practice, instrumentation teams will evaluate the entire measurement loop — from the field sensor through to the control system — to ensure signal integrity, protocol compatibility, and physical fit are all maintained.

For installations previously using the FMU230 or FMU231 with a 2-wire 4–20 mA loop connected to a Siemens S7-300 or S7-400 analog input module (such as the SM 331), the FMU42-APB2A22A retains full loop-powered compatibility. No changes to the existing cable run or junction box wiring are required in most cases, provided the loop supply voltage is within the 10.5–35 V DC operating range. Where the legacy transmitter was connected via a Pepperl+Fuchs or MTL HART multiplexer, the FMU42-APB2A22A’s HART 7 output is backward-compatible with HART 5/6 masters, ensuring uninterrupted asset management communication.

For PROFIBUS PA segments — common in Emerson DeltaV, ABB System 800xA, or Siemens PCS 7 environments — the APB2A22A variant is specifically configured for bus-powered PROFIBUS PA operation. Engineers migrating from older FMU41 units with PROFIBUS PA output will find that the FMU42-APB2A22A uses the same GSD file structure and standard PROFIBUS PA profile Class B, simplifying re-commissioning in the DCS engineering station. Segment couplers such as the Pepperl+Fuchs SK2 or R. Stahl IS1+ do not require reconfiguration when the new transmitter is substituted on the same PA segment.

In control cabinet environments where space is constrained, the FMU42-APB2A22A’s compact transmitter head is compatible with standard DIN rail-mounted power conditioners and PROFIBUS PA segment power supplies. If the existing installation uses a Endress+Hauser RN221N power conditioner or a similar unit, no modifications to the cabinet layout are necessary. For sites that require signal isolation between the field loop and the control system, a Endress+Hauser RMA42 or RMA422 signal conditioner can be inserted inline without affecting the FMU42-APB2A22A’s output characteristics.

Process connection adaptation is straightforward for most tank nozzle configurations. The FMU42-APB2A22A uses a G 2 or NPT 2 threaded process connection. Sites with existing G 1½ or NPT 1½ nozzles can use a standard stainless steel reducing adapter, available from most instrumentation suppliers, to maintain a sealed, vibration-resistant installation. The sensor’s extended temperature rating (–40 to +80 °C) also means it is suitable for outdoor installations or unheated storage tanks where the legacy FMU40 may have been marginal in winter conditions.

For programming and configuration, the FMU42-APB2A22A is fully supported by Endress+Hauser’s FieldCare and DeviceCare software via a Commubox FXA195 HART modem or a Commubox FXA291 service interface. Sites already using FieldCare for asset management of other Prosonic S or Liquiline devices will find the FMU42-APB2A22A integrates into the existing device library without additional licensing. For PROFIBUS PA commissioning, the standard PA DeviceMaster or a Softing PROFIBUS analyzer can be used to verify address assignment and cyclic data exchange before the transmitter is placed in service.

Retrofit Guidance FAQ

Q: Can I reuse the existing 2-wire cable when replacing an FMU40 or FMU41 with the FMU42-APB2A22A?
A: Yes. The FMU42-APB2A22A is loop-powered on 4–20 mA / HART and operates on the same 2-wire principle as the FMU40 and FMU41. Provided the cable cross-section and loop resistance are within specification, no rewiring is required. Verify that the loop supply voltage at the transmitter terminals is at least 10.5 V DC under maximum load.

Q: Is the PROFIBUS PA GSD file from the legacy FMU41 compatible with the FMU42-APB2A22A?
A: The FMU42-APB2A22A uses an updated GSD file. While the device profile is PROFIBUS PA Class B (compatible), it is recommended to import the new GSD file into your DCS engineering station (e.g., Siemens PCS 7 SIMATIC Manager or ABB 800xA Control Builder) and re-download the configuration to the PA segment coupler. This ensures all extended diagnostic parameters are available.

Q: Will the FMU42-APB2A22A fit in the same tank nozzle as the FMU230/FMU231?
A: The FMU42-APB2A22A uses a G 2 / NPT 2 process connection, which is one size larger than the G 1½ / NPT 1½ used on the FMU230/FMU231. A stainless steel reducing adapter is required. The sensor’s beam angle and blanking distance should also be re-verified against the tank geometry using Endress+Hauser’s Applicator sizing tool before installation.

Q: How do I transfer the configuration from the old transmitter to the FMU42-APB2A22A?
A: Use FieldCare or DeviceCare to upload the configuration from the legacy device (if still operational) and use it as a reference for manual parameter entry on the FMU42-APB2A22A. Key parameters include measuring range (empty/full calibration), blocking distance, damping, and output scaling. The FMU42-APB2A22A’s parameter structure follows the standard Prosonic S menu layout, which is consistent across the FMU42, FMU43, and FMU44 product family.

Q: What is the physical installation space requirement for the FMU42-APB2A22A?
A: The FMU42-APB2A22A transmitter head has a compact form factor compatible with standard G 2 / NPT 2 nozzle installations. The overall sensor length depends on the selected sensor variant. Ensure a minimum clearance of 200 mm above the maximum product level (blocking distance) is maintained. For installations in confined spaces or with low tank headroom, consult the datasheet for the exact blocking distance of the APB2A22A sensor configuration.

Q: Is the FMU42-APB2A22A suitable for hazardous area installations?
A: The FMU42-APB2A22A is available in Ex-rated variants. The APB2A22A order code should be verified against the applicable Ex certificate (ATEX, IECEx, or FM) for the installation zone. Contact TOPNLMS to confirm the Ex approval status of the specific unit in stock.

Warranty Assurance

Every FMU42-APB2A22A unit supplied by TOPNLMS is covered by a 12-month warranty from the date of shipment. Prior to dispatch, each unit undergoes a pre-shipment functional inspection that includes visual examination, terminal integrity check, and where applicable, power-on verification of the display and output signal. Units are packed in anti-static, shock-absorbing packaging suitable for international air and sea freight.

In the event of a warranty claim, TOPNLMS provides a replacement or repair service with a target response time of 3 business days from receipt of the returned unit. Customers are required to provide the original order number and a brief description of the fault. Return shipping costs for confirmed warranty defects are covered by TOPNLMS for orders within mainland China; international customers should contact us to confirm the applicable return logistics arrangement.

TOPNLMS maintains stock of the FMU42-APB2A22A and related Prosonic S accessories to support rapid fulfillment for both planned maintenance shutdowns and emergency replacement scenarios. Standard lead time from order confirmation to shipment is 1–3 business days for in-stock units. Express air freight to major international destinations is available on request.

For procurement inquiries, technical pre-sales support, or warranty claims, contact the TOPNLMS team directly:

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