In an ABB robot system, most people focus on drives, motors, and the controller. But the robot only moves “intelligently” if its position feedback is trustworthy every single cycle. ABB 3HAC044168-001, commonly referenced as RMU101, is part of that feedback chain: it is an SMB (Serial Measurement Board / Serial Measurement Unit) variant with a 3-pole battery contact used in ABB robot manipulators. In ABB product manuals, RMU101 is explicitly shown as “RMU101 3HAC044168-001” when describing SMB boards with 3-pole battery contact.
This matters for uptime because the SMB is tied to the robot’s measuring system and battery-backed data used to avoid loss of synchronization. ABB manuals warn that when a battery low alert appears, a recommended way to avoid an unsynchronized robot is to keep power on until replacement is performed, and they associate the 3-pole SMB board with RMU101 (3HAC044168-001).
Product identification table
| Field | Information |
|---|---|
| Manufacturer | ABB |
| Part number | 3HAC044168-001 |
| Common designation | RMU101 |
| Functional category | SMB / serial measurement unit / serial measurement board (measurement system component) |
| SMB battery contact type | 3-pole battery contact (RMU101 / RMU102 family) |
| Documented usage context | “Replacing the serial measurement unit and the battery pack” procedures in ABB robot manuals |
| Battery compatibility note | 3-pole battery unit 3HAC044075-001 “can only be used with SMB board 3HAC044168-001” in spare-parts documentation |
What the RMU101 SMB does in a robot (plain-English version)
A robot’s controller needs continuous position information from the manipulator. The SMB/RMU is the part in the robot (often located in the base area) that sits close to the measuring system hardware and helps interface those measurement signals back to the controller. ABB documentation treats it as a distinct replaceable unit (the “serial measurement unit/board”), and it is serviced together with a battery pack that supports backup behavior.
If you’re writing a product page for buyers, the important message is not “it’s a PCB.” The important message is: this is a measurement-system spare part that helps preserve correct robot position referencing and supports stable operation—especially across power-off periods, battery conditions, or service events.
The battery-backed detail that actually drives maintenance decisions
ABB manuals describe a battery low alert (38213 Battery charge low) and connect it directly to the measuring system battery replacement process. They explicitly mention RMU101 3HAC044168-001 as one of the SMB boards with 3-pole battery contact, and state a typical new-battery lifetime of 36 months for that 3-pole SMB board type.
ABB also documents that there are two SMB variants (2-pole and 3-pole battery contact). The 3-pole variant has a longer battery lifetime, and ABB emphasizes ordering the correct spare parts and not replacing the battery contact.
In spare parts documentation for other ABB robot families, ABB further clarifies compatibility: a 3-pole battery unit is listed as only usable with the SMB board 3HAC044168-001.
This is not cosmetic; it’s procurement-critical. Many “wrong part” purchases happen because someone buys “an SMB battery” without matching the contact type, or buys the wrong SMB revision without checking the correct battery ecosystem.
Where this part appears in ABB documentation (why that’s valuable for buyers)
ABB’s manuals don’t treat RMU101 as an abstract electronics item; they treat it as a serviceable robot component with:
-
a defined replacement procedure (“Replacing the serial measurement unit and the battery pack”)
-
explicit safety guidance and cautions (including ESD precautions to prevent damage)
-
spare-parts list references and system-level warnings about avoiding unsynchronization during battery events
That documentation footprint is a big advantage for search and for buyer trust: it anchors the part number to a real maintenance workflow instead of marketing claims.
Typical replacement triggers (what buyers search for)
In practice, RMU/SMB replacements are usually driven by one of these situations:
-
Battery-related service events
ABB’s battery low alert guidance pushes a planned replacement cycle. RMU101’s 3-pole battery ecosystem is part of that. -
Measuring system faults or loss-of-sync risk
ABB explicitly discusses avoiding an unsynchronized robot during battery replacement by keeping controller power on until the battery can be replaced. -
Physical damage / contamination / incorrect handling
The SMB is an electronics unit inside the robot; ABB highlights ESD precautions during repair work because ESD can damage electronics.
Procurement and compatibility checklist (highly recommended)
| Check | Why it matters |
|---|---|
| Confirm the exact part number: 3HAC044168-001 | ABB explicitly identifies RMU101 with this part number in manuals |
| Confirm SMB battery contact type (3-pole vs 2-pole) | ABB documents two variants and different battery behavior |
| Match the correct battery unit ecosystem | ABB spare parts documentation states the 3-pole battery unit can only be used with SMB board 3HAC044168-001 |
| Plan service timing around battery low alerts | ABB recommends keeping controller power on until replacement to avoid unsync risk |
| ESD-safe handling during installation | ABB includes ESD precautions in repair sections |
Installation notes for a product page (keep it safe and credible)
A public-facing product introduction should avoid inventing electrical specs unless you have an ABB datasheet for this exact part number. What you can say credibly—because ABB manuals support it—is:
-
RMU101 is a serial measurement unit/board used with SMB systems (3-pole battery contact variant).
-
Battery replacement is a defined service activity in ABB robot manuals, and RMU101 is explicitly named in that context.
-
ABB provides warnings and cautions (including ESD handling) around this procedure.
This keeps the page accurate, indexable, and defensible.
Summary (search-friendly and buyer-oriented)
ABB 3HAC044168-001 (RMU101) is an ABB robot SMB/serial measurement board or unit associated with 3-pole battery contact measuring systems. ABB documentation ties RMU101 directly to battery-backed measuring system maintenance and provides lifecycle guidance (typical 36-month new-battery life for the 3-pole SMB type), plus compatibility notes that the 3-pole battery unit is only usable with SMB board 3HAC044168-001.
