Honeywell STT17H-BS Replacement for STT17H Series

Product Overview

Honeywell STT17H-BS Replacement for STT17H Series: Seamless Transition from Legacy Temperature Transmitters

Upgrading or replacing a legacy Honeywell temperature transmitter in an active process control loop demands precision, speed, and zero tolerance for signal interruption. The Honeywell STT17H-BS is a DIN Rail-mounted Smart Temperature Transmitter engineered for the STT17H Series platform, delivering HART-protocol communication over a standard 4–20 mA two-wire loop. Whether you are retiring an end-of-life STT17H-A, migrating from an older STT25H or STT350 field-mount transmitter, or consolidating a distributed temperature measurement network onto a unified DIN Rail architecture, the STT17H-BS provides a validated, drop-in-compatible upgrade path that preserves your existing wiring infrastructure and HART device descriptors.

The STT17H-BS accepts universal sensor inputs — including Type J, K, T, E, R, S, B thermocouples and 2-, 3-, or 4-wire RTD configurations (Pt100, Pt200, Pt500, Pt1000, Ni100, Ni120) — making it directly interchangeable with the majority of Honeywell STT17H-series variants without rewiring the field junction box. The 4–20 mA output is fully HART 5/7 compliant, allowing the device to be commissioned, ranged, and diagnosed using any HART-compatible handheld communicator such as the Honeywell MC Toolkit or a third-party HART 475 Field Communicator without modifying the host DCS or PLC configuration.

In control cabinets where space is constrained, the DIN Rail form factor of the STT17H-BS eliminates the need for field-mount enclosures or additional conduit runs. The unit clips directly onto standard 35 mm DIN Rail, occupying minimal panel width and integrating cleanly alongside Honeywell STT17H-series terminal blocks, Weidmüller or Phoenix Contact signal isolators, and 24 VDC loop power supplies. For systems using a Honeywell HC900 Hybrid Controller or a Experion PKS C300 Controller with analog input modules, the STT17H-BS connects directly to the existing AI channel wiring without any signal conditioning changes.

Migration from a Honeywell STT25H or STT350 field transmitter to the STT17H-BS DIN Rail architecture is straightforward: the two-wire 4–20 mA loop wiring is retained at the marshalling cabinet, the HART device address is reassigned via the communicator, and the transmitter is re-ranged to match the original process variable span. No PLC or DCS I/O card replacement is required, and the existing loop power supply — typically 24 VDC at the panel — remains unchanged. This approach reduces retrofit labor to under two hours per loop in most installations.

For larger migration projects involving multiple temperature loops, the STT17H-BS is frequently deployed alongside Honeywell STT17H-series DIN Rail mounting kits, HART multiplexers for batch commissioning, and Honeywell Experion Asset Manager for centralized device health monitoring. In Profibus or FOUNDATION Fieldbus environments, a HART-to-Fieldbus gateway can bridge the STT17H-BS into the existing fieldbus segment without replacing the host I/O card, preserving the investment in existing bus infrastructure.

Power supply requirements are minimal: the STT17H-BS operates on loop power from 11.5 VDC to 42.4 VDC, compatible with virtually all existing 24 VDC panel power supplies and Honeywell or Phoenix Contact DIN Rail power supply modules already installed in the control cabinet. The unit is rated for ambient temperatures from –40 °C to +85 °C, making it suitable for both climate-controlled control rooms and outdoor marshalling enclosures in harsh industrial environments.

For facilities managing spare parts inventory across multiple plant areas, the STT17H-BS is an ideal consolidation SKU: a single model covers the majority of thermocouple and RTD input types, reducing the number of distinct transmitter part numbers held in the storeroom. Combined with the HART universal device descriptor, a single STT17H-BS unit can be reconfigured on the bench to replace any STT17H-series variant, minimizing emergency procurement lead times and reducing the risk of production downtime caused by obsolete spare parts.

Compatibility Comparison Table

Seamless Upgrade Solutions

A complete STT17H-BS migration typically involves coordinating several related components already present in the control system. The existing Honeywell STT17H DIN Rail mounting bracket and terminal block assembly can be reused directly, eliminating the need to modify the panel layout. Where signal isolation is required between the transmitter loop and the DCS analog input card, a Phoenix Contact MACX MCR-SL signal isolator or equivalent DIN Rail isolator can be inserted inline without affecting the HART communication signal.

For systems using a Honeywell HC900 Hybrid Controller with analog input modules, the STT17H-BS connects to the existing AI-900 or HAI-900 input card wiring without modification. In Experion PKS environments, the transmitter integrates with C300 Controller analog input channels via the existing marshalling cabinet wiring. Where multiple STT17H-BS units are deployed across a temperature measurement network, a HART multiplexer — such as the Honeywell HART MUX or a third-party equivalent — enables simultaneous commissioning and diagnostics of all devices from a single workstation, significantly reducing loop-by-loop commissioning time.

In applications where the control cabinet also houses Honeywell UDC2800 or UDC3500 Universal Digital Controllers, the STT17H-BS can feed the 4–20 mA input directly, replacing a failed head-mount transmitter without modifying the controller’s input configuration. For installations requiring galvanic isolation between the sensor and the control system — common in high-voltage industrial environments — a DIN Rail signal isolator with HART transparency ensures the HART signal passes through without attenuation, preserving remote diagnostics capability.

Panel power for the STT17H-BS loop is typically sourced from an existing 24 VDC DIN Rail power supply already installed in the marshalling cabinet. No additional power supply is required in most retrofit scenarios. Where the cabinet also contains Honeywell STT17H-series intrinsic safety barriers for hazardous area applications, the STT17H-BS is compatible with standard Zener barriers and galvanic isolators rated for Zone 1 / Division 1 installations.

Retrofit Guidance FAQ

Q: Can I reuse the existing field wiring when replacing an STT17H-A with the STT17H-BS?
A: Yes. The STT17H-BS uses the same 2-wire 4–20 mA loop connection. The existing field cable is retained at the marshalling terminal block. No rewiring is required at the field junction box or the DCS I/O card.

Q: Is the STT17H-BS backward compatible with HART 5 host systems?
A: Yes. The STT17H-BS supports both HART 5 and HART 7. In HART 5 host environments, the device operates in HART 5 mode automatically. No host system reconfiguration is required.

Q: How do I re-range the STT17H-BS to match the original process variable span?
A: Connect a HART communicator (e.g., Honeywell MC Toolkit or HART 475) to the loop terminals. Navigate to the ranging menu, enter the lower range value (LRV) and upper range value (URV) matching the original transmitter configuration, and write to the device. The process takes approximately 5 minutes per loop.

Q: Does the DIN Rail mounting of the STT17H-BS require any panel modifications?
A: No. The STT17H-BS clips onto a standard 35 mm DIN Rail. If the existing panel uses a field-mount transmitter, the DIN Rail can be added to the marshalling cabinet without structural modification. The unit’s compact width minimizes space impact.

Q: Can the STT17H-BS replace an STT25H or STT350 field-mount transmitter?
A: Yes, with a wiring relocation. The field sensor wiring is extended to the marshalling cabinet terminal block, and the STT17H-BS is installed on the DIN Rail. The 4–20 mA loop output connects to the existing DCS AI channel. This approach is commonly used when consolidating field-mount transmitters into a centralized DIN Rail panel during a control system modernization project.

Q: What happens to the HART device descriptor in the DCS after replacement?
A: The DCS HART device descriptor references the device type and revision. After installing the STT17H-BS, perform a HART device scan from the DCS or asset management system to update the device record. In most Experion PKS and HC900 environments, this is a non-disruptive operation that does not interrupt the 4–20 mA process signal.

Warranty Assurance

Every Honeywell STT17H-BS unit supplied by TOPNLMS is covered by a 12-month warranty from the date of shipment. Prior to dispatch, each unit undergoes functional verification including loop output calibration check, HART communication test, and sensor input continuity verification. Units that do not meet factory specification are quarantined and not shipped.

In the event of a warranty claim, TOPNLMS provides a replacement unit or full refund within the warranty period. Our after-sales response time is within 24 hours for warranty inquiries submitted by email. Replacement units are dispatched from our Xiamen warehouse with priority shipping to minimize your plant downtime.

For procurement teams managing critical spare parts programs, TOPNLMS maintains buffer stock of the STT17H-BS to support emergency orders with same-day or next-day dispatch. Volume pricing is available for orders of 5 units or more. All units are shipped with original manufacturer documentation, calibration records, and a TOPNLMS inspection certificate.

To place an order or request a compatibility assessment for your specific installation, contact our technical sales team directly:

• Email: [email protected]
• Phone / WhatsApp: +86 18359293191
• Website: https://topnlms.com