Rosemount 644 Temperature Transmitter Decoder
Paste a 644 model code (head, field, or rail mount) and read the transmitter type, output protocol, enclosure, diagnostics, display, and the full option string in plain English. Built from Emerson PDS 00813-0100-4728 Rev WH plus the rail-mount PDS, every option source-cited.
A grammar-driven decoder for the Rosemount 644 Temperature Transmitter, the most common Emerson temperature transmitter in process plants. The 644 model code is short by design: a transmitter type (head single H, head dual S, field single F, field dual D, rail single R, rail dual T) and an output (HART A, FOUNDATION Fieldbus F, PROFIBUS PA W), then a long string of option adders. The decoder reads the type and output, then matches every option (Hot Backup diagnostics, enclosures in aluminum / cast SST / polished SST, mounting brackets, LCD display and LOI, software configuration, enhanced accuracy, alarm levels, line filter, sensor trim, 5-point calibration, calibration and traceability certificates, custody transfer, safety certification, shipboard approvals, transient protection, cable glands, conduit connectors, HART revision, assemble-to, warranty, and the full hazardous-location approval list) by longest match against the PDS dictionary. Crucially, the 644 model code does NOT encode the sensor: the RTD or thermocouple type, range, and span are configured separately, so the decoder makes that explicit rather than pretending to know the measurement. Head and field mount come from PDS 00813-0100-4728 Rev WH; rail mount (types R/T and option RK) come from the separate rail PDS 00813-0300-4728 Rev AA. Constraint rules fire when Fieldbus or PROFIBUS is ordered on a non-single-sensor-head type, or when Hot Backup is ordered without a dual-sensor type.
Decode the higher-feature 3144P (dual sensor, Hot Backup, X-well) when the 644 is not enough
Rosemount 3144P Decoder →Decode the 848T multi-input transmitter for high point-count temperature installations
Rosemount 848T Decoder →Decode the pressure side of the same Emerson ecosystem
Rosemount 3051 Decoder →Relate the configured temperature span to expected 4-20 mA output on a HART loop
4-20 mA Signal Helper →How It Works
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Start with the 644 prefix
Begin the code with 644. The decoder reads the transmitter type and output next, then treats everything else as option adders.
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Read the transmitter type
Position 1 is the type: H head single, S head dual, F field single, D field dual, R rail single, T rail dual. This single character carries both the form factor (head / field / rail) and the sensor count (single / dual).
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Read the output
Position 2 is the output: A HART 4-20 mA, F FOUNDATION Fieldbus, W PROFIBUS PA. Fieldbus and PROFIBUS are single-sensor-head only; the decoder warns if they appear on any other type.
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Walk the option string
Diagnostics, enclosure, bracket, display, software, performance, alarm level, line filter, sensor trim, calibration, custody, safety, shipboard, transient, cable gland, conduit connector, HART revision, assemble-to, warranty, and approvals are matched by longest match. Each shows its category, meaning, and PDS page.
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Note that the sensor is not in the code
The decoder makes explicit that the RTD/thermocouple type, range, and span are configured separately, not encoded. Use option XA (assemble-to) and the Configuration Data Sheet (option C1) to know the actual measurement.
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Read the constraint warnings
Warnings fire only on real conflicts: Fieldbus/PROFIBUS on a non-H type, Hot Backup (DC) on a single-sensor type, a field-mount enclosure (D1/D2) on a non-field type, or the RK rail version on a non-rail type.
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Export the decode
PDF export gives a branded, page-break-safe report; CSV export packages the same fields; the share URL reproduces the decode for a coworker.
Built For
- Maintenance tech decoding a 644 head-mount nameplate to order a matching spare without pulling the sensor
- Reliability engineer confirming a dual-sensor 644 (type S) is specified before promising Hot Backup failover on a critical loop
- Project engineer checking that a Fieldbus 644 order is on the single-sensor head type, because Fieldbus is not offered on dual/field/rail
- Planner decoding a rail-mount 644 (type R or T) and confirming the RK HART 7 version against the separate rail PDS
- Buyer verifying a NACE / safety-certified 644 has the QT certificate and the right approval combination
- Estimator bulk-decoding 644 codes from an instrument index to pull out mount style and output
- Inspector confirming a custody-transfer 644 (option D4) is a HART build, since custody transfer is not offered on Fieldbus
Features & Capabilities
Head, field, and rail in one decoder
Types H/S/F/D come from the head/field PDS; rail types R/T and the RK HART 7 version come from the separate rail PDS. Both are decoded under the single 644 model number with rail-specific rows cited to the rail document.
Output-vs-type constraint enforcement
FOUNDATION Fieldbus and PROFIBUS PA outputs are flagged when ordered on anything but the single-sensor head (type H), because the PDS restricts them there. Dual-sensor, field, and rail builds are HART only.
Hot Backup needs dual sensor
The DC diagnostics option (Hot Backup and sensor drift alert) is flagged unless the transmitter type is dual-sensor (S head or T rail). This is the most common 644 spec mistake and the decoder catches it.
Sensor-not-in-code honesty
The decoder does not pretend to know the measurement. It states plainly that the sensor type, range, and span are configured separately and points at the assemble-to option and the Configuration Data Sheet.
Full enclosure and approval coverage
Every enclosure code (aluminum, cast SST, polished SST junction boxes and connection heads, plus field-mount dual-compartment housings) and the full hazardous-location approval list are decoded with PDS pages.
Source-cited, confidence-labeled
Every option carries its PDS page and a confidence label. Rail-only rows are explicitly cited to the rail PDS so the two-document sourcing is transparent.
PDF and CSV export
Page-break-safe branded PDF and CSV export of the full decode, including the constraint warnings and field notes.
Tripwire test suite
Canonical integrity, golden-path, negative-path, confidence coverage, source-page coverage, cross-reference slug validation, and summary snapshot tests run on every change.
Comparison
| Transmitter type | Mount | Sensors | Outputs available | Hot Backup? |
|---|---|---|---|---|
| H | Head | Single | HART, Fieldbus, PROFIBUS PA | No |
| S | Head | Dual | HART only | Yes (DC) |
| F | Field | Single | HART only | No |
| D | Field | Dual | HART only | Yes (dual), DC per PDS is S/T |
| R | Rail | Single | HART only | No |
| T | Rail | Dual | HART only | Yes (DC) |
References
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Frequently Asked Questions
Learn More
Rosemount 2051 Ordering Code Guide: 2051C, 2051T, 2051G and the 2051-vs-3051 Decision
Plain-language guide to the Rosemount 2051 pressure transmitter ordering matrix. How to read 2051C coplanar, 2051T and 2051G in-line codes, why pressure range depends on measurement type, how output protocol pulls in housing and approval constraints, and the accuracy-class decision between the 2051 and the higher-accuracy 3051. Companion to the Rosemount 2051 Decoder.
Rosemount 644 Ordering Code Guide: Head, Field, Rail and the Fieldbus / Hot Backup Constraints
Plain-language guide to the Rosemount 644 temperature transmitter ordering code. How to read head, field, and rail-mount codes, why the sensor type is not in the model code, and the two constraints that catch people: FOUNDATION Fieldbus and PROFIBUS PA are single-sensor head only, and Hot Backup requires a dual-sensor build. Companion to the Rosemount 644 Decoder.
Rosemount 3144P Ordering Code Guide: Single vs Dual Sensor, X-well, and the HART / Fieldbus Split
Plain-language guide to the Rosemount 3144P temperature transmitter ordering code. How to read housing, output, and measurement configuration, why single vs dual sensor gates Hot Backup and the dual-input modes, what X-well surface measurement is and is not for, and how FOUNDATION Fieldbus splits the option list. Companion to the Rosemount 3144P Decoder.
Rosemount 848T Ordering Code Guide: Channel Count, the S002 Cert Trap, and the Wireless Build
Plain-language guide to the Rosemount 848T multi-input temperature transmitter ordering code. How output sets protocol and channel count (Fieldbus 8, wireless 4), the S002 4-20 mA input certification trap, what a wireless build requires, and why the per-channel sensor map lives on the Configuration Data Sheet. Companion to the Rosemount 848T Decoder.
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