H-MTD Cable Assemblies: How to Choose Single-Port, Dual-Port and Quad Breakouts

What Single-Port, Dual-Port, and Quad Mean in an H-MTD Housing

H-MTD (High-Speed Modular Twisted-Pair Data) is a 100 Ω differential connector system designed for high-speed automotive links. Unlike single-ended coaxial connectors, each standard H-MTD data port carries one balanced twisted pair across 2 signal contacts.

In the Rosenberger H-MTD portfolio and the Rosenberger H-MTD Catalog 2024, the housing designation tells you how many of these 2-contact differential ports are packaged inside a single outer shell:

• 

  Single-port housing: Contains 1 differential data port (2 signal contacts).

• 

  Double (dual-port) housing: Integrates 2 independent differential data ports (2×2 signal contacts) in one shell.

• 

  Quad-port housing: Integrates 4 independent differential data ports (4×2 signal contacts) in one shell.

Standard shielded H-MTD connectors (E6 series) pair with matched 100 Ω shielded twisted-pair (STP) cables. For specialized harness requirements, the broader family also includes six-port housings (6×2 signal contacts), an unshielded H-MTDe series (E9) built for unshielded twisted-pair (UTP) cables, and hybrid H-MTD+6 connectors that add six MQS power contacts alongside the data ports.

Why Two Connector Ends Do Not Make a Dual-Port Cable

Every point-to-point jumper has two ends (Side A and Side B). A cable terminated with one single-port connector on Side A and one single-port connector on Side B carries one twisted pair and remains a single-to-single assembly—not a "dual-port" cable.

Likewise, when a datasheet or product title describes a single-port jumper as plug-to-plug or jack-to-jack, it is specifying the contact and housing gender on each end. "Plug-to-plug" means both ends use male plug interfaces; it does not mean "plug-and-play."

How H-MTD Differs from Coaxial FAKRA/Mini FAKRA and 4-Contact HSD

When reviewing vehicle harness drawings, it helps to separate H-MTD from two other high-speed automotive interfaces that often appear on the same bill of materials:

• Coaxial FAKRA and Mini FAKRA vs. Differential H-MTD: FAKRA and Mini FAKRA are coaxial interfaces that transmit unbalanced signals over a center conductor and outer shield (typically for RF antennas or coaxial camera links), whereas each H-MTD cavity carries a balanced 100 Ω differential pair across two contacts. When a harness includes both coaxial and differential paths, see our Mini FAKRA vs. FAKRA selection guide to distinguish their coding and signal roles.
• 4-Contact HSD vs. Dual-Port H-MTD: Both interfaces contain four signal contacts, but they serve different cable constructions. A standard 4-contact HSD interface places all four contacts inside a single shielded cavity terminated to one four-conductor star-quad cable (see our guide to HSD cables). A dual-port H-MTD housing divides its shell into two isolated 2-contact cavities (2×2), terminating two separate twisted-pair cables that can run either to a matching dual-port header or to two separate single-port interfaces.

Choosing Between Single-to-Single, Multiport-to-Multiport, and Breakout Assemblies

Once you know the housing port counts on both devices, match the cable topology to the physical layout of the endpoints.

Single-to-Single Assemblies

A single-to-single assembly links one single-port Electronic Control Unit (ECU), sensor, or test port directly to another single-port interface. Both Side A and Side B must be specified independently for gender (plug vs. jack), mechanical coding, straight vs. right-angle cable exit, and sealing.

Choosing between a shorter jumper (such as 0.5 m or 1 m) and a longer cable (such as 5 m) in the same single-port configuration depends on the physical routing path and the channel's electrical loss budget. Because longer runs add insertion loss, always verify that the total length meets the target protocol's channel limit rather than treating different lengths as universally interchangeable.

Dual-to-Dual and Quad-to-Quad Multiport Assemblies

When two connected units—such as a zonal gateway and a central compute module or switch—consolidate two or four differential channels into matching multiport printed circuit board (PCB) headers, a dual-to-dual or quad-to-quad trunk assembly mates all channels in one latching motion. Grouping adjacent links into a single multiport header reduces board footprint and speeds up harness installation between high-density modules.

Dual-to-2×Single and Quad-to-4×Single Breakout Assemblies

When one endpoint uses a space-saving multiport header on a controller or capture unit while the opposite endpoints are physically separate single-port devices, a dual-to-2×single or quad-to-4×single breakout (fan-out) assembly bridges the two layouts.

A passive breakout is not an Ethernet switch. Inside a quad-to-4×single harness, each of the four cavities in the quad housing connects directly to one dedicated single-port branch over its own twisted pair. The cable cannot take a single active port and split or broadcast its traffic to four devices; the host header must already provide four independent channels. Because each branch is an isolated point-to-point link, cross-plugging two branches that share the same interface series, gender, and coding may connect a peripheral to an unintended controller port, depending on how the host hardware assigns its ports.

How to Read an H-MTD Assembly Title Using a Quad-to-4×Single Example

Catalog titles and part strings compress several housing and cable specifications into a single line. Using the quad-to-4×single assembly referenced above as a concrete example:

H-MTD Consolidated endQuad Jack E6K14D-1CAZ5-Z to Branch endsSingle Jack E6K14A-1CAZ5-Z*4 Automotive Ethernet Cable Assembly with 1M GG 2Speed 251 Wire 100Ω Shielded Twisted Pair Cable

Each segment of these referenced Rosenberger H-MTD catalog codes identifies a specific part of the build:

• Connector Gender (K vs. S): In the E6K... and E6S... numbering structure, K denotes a female jack and S denotes a male plug (such as E6S10A-1CAZ5-Z for a straight single-port plug). Because both ends of a cable assembly must be defined, the title states whether the build is Jack to Jack, Plug to Plug, or Jack to Plug.
• Housing Variant and Port Count (E6K14D vs. E6K14A*4): On the consolidated end, E6K14D-1CAZ5-Z specifies one quad jack housing (D), whereas E6K14A-1CAZ5-Z*4 on the breakout end specifies four separate single-port jack housings (A, multiplied by *4). By contrast, a title written as Quad Jack to Jack E6K10D-1CAZ5-Z describes a quad-to-quad trunk with one four-port housing on each end. In these specific Rosenberger straight cable-connector series, 10A / 10B / 10D designate standard housings and 14A / 14B / 14D designate waterproof connector variants.
• Cable Group (CA) vs. Explicit Wire Type: Inside -1CAZ5-, CA identifies a 100 Ω shielded cable group matched to the connector's crimp termination (the Rosenberger catalog lists GG 2Speed 251 and LEONI Dacar 686-3 as examples under group CA, LEONI Dacar 647-4 under group BZ, and AQ for unshielded cables paired with E9 H-MTDe connectors). Because a cable group covers more than one compatible wire, CA alone does not uniquely identify GG 2Speed 251—always check the explicit wire name stated in the specification.
• Mechanical Coding Suffix (-Z): The trailing -Z specifies the housing's mechanical coding (water blue neutral coding for codings A–F in the catalog). Because lighting and molding batches can shift how housing colors look in photos, always verify the coding letter and keying geometry against the drawing rather than judging by color alone.

Practical note on part codes: The letter and digit positions explained above apply to the specific Rosenberger catalog series cited here rather than serving as a universal rule across all manufacturers or every H-MTD sub-series. Likewise, referencing a catalog connector code in a third-party assembly title describes the interface configuration—it does not imply OEM manufacturing origin or prove that the finished harness has been validated as a complete IP67-sealed system.

How to Document a Multiport Breakout: Branch Labels, Destinations, and Length Datums

A product photograph or summary title for a quad-to-4×single assembly confirms that one four-port housing fans out into four single-port leads, but it cannot show which branch connects to which cavity inside the quad shell, or exactly where a stated nominal length starts and ends.

In multiport H-MTD pinning standards (such as Rosenberger RN_143-02 for double and RN_143-04 for quad), the apparent position of each numbered cavity depends on the specified viewing plane (View A, View B, Side A, Side B). Never assume a generic "top-left is Port 1" rule or assume that a branch label automatically matches a catalog cavity number.

In addition, whenever multiple single-port device interfaces share the same series, gender, and mechanical coding, any matching branch connector can physically mate with any of those device ports. Recording cavity-to-branch continuity on a controlled drawing and applying physical labels to each lead prevents cross-connection during installation.

Example: Specifying Branch Labels and Routed Lengths on a 4-Branch Harness

Consider a separate example (independent of the off-the-shelf 1 m assembly discussed above) in which a four-port ECU header fans out to four camera modules that are each designed with a matching differential H-MTD interface (many automotive cameras use coaxial interfaces instead, so this setup applies specifically to differential H-MTD camera nodes).

In this example specification, all four breakout branches terminate in single-port Z-coded jacks (E6K14A-1CAZ5-Z), and exact cavity-to-branch contact mapping is defined on the project's harness drawing. To make the length values unambiguous, the project defines each branch's overall length (L_overall) along the harness path from the mating face of the quad jack housing to the mating face of that branch's single-port jack, including a 250 mm shared bundled section between the quad housing mating face and the breakout split point.

Under this project convention, the 250 mm shared section is included in each overall length. The remaining reach after the split is 750 mm for the front branches and 1250 mm for the rear branches. These are routed lengths between mating faces, not wire-cutting or stripping dimensions.

Connecting an Automotive Ethernet ECU to a PC: Cable Assembly vs. Media Converter Roles

On a development or validation bench, a common task is connecting an Automotive Ethernet Device Under Test (DUT)—such as an ECU or sensor with an H-MTD interface—to a standard RJ45 network port on a laptop or desktop PC.

When Active PHY Conversion Is Required

For a bench link using 100BASE-T1 or 1000BASE-T1, data travels over a single 100 Ω balanced twisted pair. Confirm the PHY standard of the device port first; the H-MTD connector alone does not identify it. A standard PC RJ45 network adapter uses 100BASE-TX / 1000BASE-T, which relies on different physical layer (PHY) signaling and pair counts.

Because the T1-side and PC-side physical layers are incompatible, connecting a 100BASE-T1 / 1000BASE-T1 H-MTD port to a standard PC 100BASE-TX / 1000BASE-T RJ45 port requires an active Media Converter—or a test interface with a built-in T1 PHY—to translate frames between the two standards. Passive wire re-pinning alone cannot convert between T1 and standard PC copper Ethernet.

At the same time, do not judge a test accessory by its connector names alone: some commercial bench adapters incorporate active conversion electronics, whereas passive fixture adapters are meant for test equipment that already contains a matching PHY.

Separating Data, Power, and Configuration on the Bench

When using dedicated automotive Ethernet media converters—such as the Intrepid RAD-Moon2 or the Technica 100/1000BASE-T1 MediaConverter series—hardware roles on the bench are split into three distinct functions:

1. Passive Differential Data Channel: A matched 100 Ω shielded single-to-single H-MTD assembly carries the differential signal pair between the T1 port on the ECU/DUT and a converter model equipped with a matching H-MTD T1 port (while a standard RJ45 patch cord connects the converter's PC-side port to the computer). Note that converter product lines vary by model—for example, within Technica's 100/1000BASE-T1 family, variants such as TE-1403 and TE-1406 provide an H-MTD interface whereas TE-1402 and TE-1405 use MATEnet—so always match the cable assembly to the exact T1 interface on your specific converter.
2. Independent Device Power: In this separately powered setup, the H-MTD assembly carries data while the media converter and ECU/DUT receive power through their own power inputs, as specified in their hardware manuals. Do not assume that connecting the H-MTD cable will also power the DUT.
3. Converter PHY Settings: Link parameters on the media converter—such as Master/Slave role, 100 Mbps vs. 1000 Mbps speed selection, and IEEE vs. legacy mode (where supported)—are configured on the converter via DIP switches, serial console, or software utility according to the specific model's manual.

If a DUT groups four independent T1 ports into one quad H-MTD header, a matched quad-to-4×single breakout assembly can fan out those four lanes so individual channels can connect to separate T1 test ports or media converters as required by your test setup.

Selecting or Specifying Your H-MTD Assembly

Once you have matched your endpoint layout to a single-to-single, dual-to-dual / quad-to-quad, or dual-to-2×single / quad-to-4×single breakout configuration, confirm the connector series, plug or jack gender, coding letter, matched cable type, and drawing-referenced branch mapping before ordering. You can explore standard single-port jumpers and multiport breakout harnesses in our Automotive Ethernet Cable Assemblies category, or submit your controlled harness drawing and branch length requirements for a custom build.