Using Mitutoyo Scales with TouchDRO

Mitutoyo Scales and Connectors at a Glance

Over the years, Mitutoyo used a few different connector types for their scales that mapped cleanly to the signal type and supply voltage. For example, scales that used a 7-pin bayonet connector were 10V sin/cos scales, and scales that used a 6-pin bayonet connector were 5V quadrature/TTL. In contrast, most of their modern AT scales use a 15-pin D-Sub connector, regardless of the signal type.

Scale Family	Signal	TouchDRO Compatible?
Digimatic Instruments with 5-pin flat SPC connector	Digimatic / SPC serial	Yes — with SPC converter
Digimatic Instruments with 6-pin round SPC connector	Digimatic / SPC serial	Yes — with SPC converter
572 Series (9-pin D-Sub connector)	Digimatic / SPC serial	Not currently supported
AT200 Series	RS-422 differential TTL quadrature	Yes — with adapter cable
AT100 Series	2 Vpp pseudo-differential sin/cos	Not currently supported
AT500 / AT715 Series	Proprietary serial (RS-485 physical)	Not currently supported
AT2-N / AT11-N (6-pin round connector)	5V TTL quadrature	Yes — with adapter cable
AT2-FN / AT11-FN (7-pin round connector)	4 Vpp sin/cos (10V supply)	Not currently supported

Digimatic / SPC Scales

Digimatic (also called SPC) is Mitutoyo's serial data protocol for handheld measurement instruments. The protocol is the same across calipers, micrometers, indicators, quill scales, and 572-series linear scales — only the physical connector and the supply voltage change between product lines. The signals are open-drain rather than standard TTL, so a Digimatic device can't be wired into a typical DRO input directly. The physical hookup to TouchDRO is different for each product line and is covered in the subsections below.

5-Pin Digimatic — Modern SPC Instruments

The 5-pin flat Digimatic connector is the standard data port on current-production Mitutoyo handheld instruments — calipers, micrometers, indicators, and the popular 053906B quill scale. The connector is sealed and proprietary, so the only practical way to read one is with a Mitutoyo-made data cable.

To connect a 5-pin Digimatic instrument to TouchDRO, use a Mitutoyo SPC data cable — part number 905338 (1m) or 905409 (2m) — between the instrument and the Mitutoyo SPC converter. The converter reads the Digimatic protocol and outputs a signal the TouchDRO adapter can read.

6-Pin Round Digimatic — Older Instruments

Older Mitutoyo Digimatic instruments use a 6-pin round connector instead of the flat 5-pin SPC plug. Electrically and protocol-wise these are the same as the modern 5-pin instruments — only the physical connector is different.

The 6-pin Digimatic connector is also Mitutoyo-proprietary, so it needs a dedicated Mitutoyo cable. Use part number 937387 (1m) or 965013 (2m) between the instrument and the Mitutoyo SPC converter.

DB9 Digimatic — 572-Series Linear Scales

The Mitutoyo 572-series are full-length linear scales designed to pair with Mitutoyo's own Digimatic counter unit. Despite the DB9 connector, the protocol on the wire is the same Digimatic serial format used by the handheld instruments — not RS-422 quadrature. That makes the DB9 pinout incompatible with the Acu-Rite-style DB9 used by most modern DROs, and a straight DB9-to-DB9 cable will not work.

The 572-series scales are not currently supported by TouchDRO. The pinout is included below for reference.

Modern AT DRO Scales (DB15)

The current generation of Mitutoyo AT scales uses a DB15 connector regardless of what the scale outputs electrically. This is the single most common source of confusion with Mitutoyo: the same connector is shared across three incompatible electrical families. Always verify which model you have before wiring. The DB15 alone doesn't tell you whether the scale is sending quadrature, sin/cos, or a proprietary serial stream.

AT200 Series — Quadrature

AT200 series scales (AT203, AT211, and similar) output a quadrature signal (differential RS-422) and run on a 5V supply. TouchDRO supports that signal natively. You can either swap the scale's DB15 connector for a DB9 male, or use a pre-made adapter cable. Either way, the scale's reference mark still works, so TouchDRO can re-establish absolute position after a power cycle.

The AT200 DB15 pinout is as follows:

If you connect the scale directly by replacing its connector, wire every +5V lead to TouchDRO's 5V pin and every ground lead to its 0V pin. AT200 scales carry two or three +5V leads. All of them have to be connected, or the scale won't work correctly.

AT100 Series — Sin/Cos

AT100 series scales (AT103, AT112-F, AT113, AT116, AT181, and similar) output a pseudo-differential analog sin/cos signal. It is similar to the more common 1 V_pp sin/cos output, but the wiring is different. Instead of two complementary pairs, these scales use a single sin line and a single cos line at 2 V_pp nominal amplitude, plus a shared common-mode reference line.

TouchDRO doesn't support sin/cos scales directly. To use AT100 or AT400 series scales with TouchDRO, they need the sin/cos-to-quadrature converter.

AT500 / AT715 — Proprietary Serial

The AT500 series is Mitutoyo's current absolute-position magnetic-scale line; AT715 is the previous-generation equivalent in the same family. Both use a proprietary serial protocol over a half-duplex RS-485 physical layer (twisted pair). TouchDRO does not support these scales yet. Please contact us if you'd like to use AT500 or AT715 scales with TouchDRO. Knowing there's demand helps us prioritize what to support next.

AT500 and AT715 scales are not currently supported by TouchDRO. The pinout is included below for identification.

ST Series Scales

Mitutoyo also makes a parallel family of ST (Separate Type, as opposed to Assembly Type) scales. ST scales mostly show up on coordinate measuring machines and metrology equipment rather than shop machine tools, and we haven't tested them ourselves. The pinouts below come from Mitutoyo's documentation, so verify them against your own scale before wiring. ST scales use several Type pinouts (A, B, C, and D), set by a letter in the model number, so matching your variant to the correct pinout matters.

Type B and Type C output a differential quadrature signal, which TouchDRO supports directly. They use a 15-pin D-Sub connector and a 5V supply, but the pinout differs from the AT200 series, so an AT200 cable won't work. We don't offer a ready-made adapter cable for ST scales, so you'll need a connector swap or a DIY adapter cable.

DB15 Pin	Signal
1, 2	0V / Signal Ground
3, 4	+5V
10	Channel A
11	Channel A (inverted)
12	Channel B
13	Channel B (inverted)
8	Reference (index)
14	Reference (inverted)
15	Frame Ground / Shield

Type A and Type D output sin/cos only, so they need the sin/cos-to-quadrature converter. Type A is single-ended 2 V_pp and shares the AT100 series pinout, so the same converter handles it the same way. Type D is differential 1 V_pp and uses a different pinout.

Signal	Type A (DB15 Pin)	Type D (DB15 Pin)
0V / Signal Ground	1, 2	12, 13, 15
+5V	3, 4	4, 5
Sin/Cos A	5	9
Sin/Cos A (inverted)	—	1
Sin/Cos B	6	10
Sin/Cos B (inverted)	—	2
Reference (index)	8	3
Reference (inverted)	—	11
Vref	7, 10	—
Frame Ground / Shield	15	—

Legacy AT2 and AT11 Scales

Before standardizing on the DB15 connector, Mitutoyo used proprietary Hirose circular connectors for the AT2 and AT11 DRO scales, as well as for many microscope and optical-comparator micrometer heads. Scales with the -N suffix used a 6-pin connector and output a single-ended quadrature signal on a 5V supply. Scales with the -FN suffix used a 7-pin connector and output a pseudo-differential sin/cos signal at 4 V_pp amplitude on a 10V supply.

AT2-N / AT11-N (6-Pin Round Connector)

The AT2-N and AT11-N use a 6-pin Hirose RM12xxx-6P round bayonet connector. They run on a 5V supply and output a TTL quadrature signal (with or without a reference line, depending on the scale model). Electrically these scales are close to modern TTL quadrature scales, so they only need a connector swap or an adapter cable to work with TouchDRO.

The pinout for the 6-pin AT2-N / AT11-N connector is as follows:

AT2-FN / AT11-FN (7-Pin Round Connector)

The AT2-FN and AT11-FN are the analog cousins of the −N scales. They use a 7-pin Hirose RM12xxx-7P round bayonet connector, run on a 10V supply, and output a pseudo-differential sin/cos signal at 4 V_pp amplitude.

AT2-FN and AT11-FN scales are not currently supported by TouchDRO. The pinout is included below for identification.

Common Wiring Notes

• Verify before powering. Wrong +5V/0V mapping can damage a scale instantly, and AT2-FN/AT11-FN run on a +10V supply — double-check the voltage before plugging anything in.
• DB15 is not universal. The same DB15 connector is shared across AT2xx (TTL quadrature), AT1xx (sin/cos), and AT500/AT715 (serial). Always confirm the model before wiring; the connector alone tells you nothing about what's on the pins.
• Cable swapping is risky. Mitutoyo cables for different families often share a connector while carrying entirely different signals, so a cable built for one model can misroute power or signals on another. Match the cable to the exact model, not just the connector.
• Keep differential pairs together. For RS-422 quadrature (AT2xx), each A/A′, B/B′, and Z/Z′ pair should stay on a twisted pair inside the adapter cable, with shielding bonded at one end.
• Multiple power and ground pins. Several Mitutoyo connectors duplicate +5V and 0V across multiple pins. The pins are not always tied together inside the scale — tie them on the cable side.

Frequently Asked Questions

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The connector on my Mitutoyo scale doesn't look like any of the connectors on this page — what is it?

Mitutoyo supplies scales to many CMM, optical comparator, and other measurement-equipment manufacturers, and those often use OEM-specific connectors or pigtail harnesses that won't match anything shown here. To pin down the wiring you usually have to work backward from the equipment the scale was originally fitted to. Send us a photo of the scale, its label, and the connector and we'll help you identify it.

How do I tell which signal type my Mitutoyo DB15 scale uses?

You can't tell from the connector — Mitutoyo uses the same DB15 across three incompatible signal families, so you have to identify the model. AT2xx scales (AT203, AT211, and similar) output RS-422 differential TTL quadrature; AT1xx scales (AT103, AT113, AT112-F, AT181) output 2 Vpp single-ended sin/cos; AT500 and AT715 use a proprietary absolute serial protocol. The model number is usually etched or printed on the scale body — check it against the tables on this page before wiring, because a quadrature input, a sin/cos input, and a serial scale are not interchangeable.

I have a non-Mitutoyo scale with a similar round connector — will it work?

Don't assume it will. Hirose is a major connector manufacturer and the RM12 series was widely used, so plenty of other equipment makers fitted the same connector — with no guarantee the pinout or electrical characteristics match Mitutoyo's. A matching connector tells you nothing about what's on the pins; identify the scale and verify its pinout and signal type before wiring anything.

I have a Mitutoyo micrometer head with a 6-pin connector — is it the same pinout as the AT2-N / AT11-N scales?

Yes — Mitutoyo's 6-pin round-connector micrometer heads use the same Hirose RM12 6-pin pinout as the AT2-N / AT11-N scales and output the same 5 V TTL quadrature, so the wiring approach is identical.

Can I use a Mitutoyo scale with a DRO other than TouchDRO?

It depends on the scale's signal type. Quadrature scales (AT2xx, and the legacy AT2-N / AT11-N) output a standard signal, and the sin/cos converter turns AT1xx and ST sin/cos scales into standard TTL quadrature — both work with any DRO that accepts that signal, provided the pinout matches. Digimatic / SPC scales are the exception: decoding that protocol is uncommon outside Mitutoyo's own counters, so most general-purpose DROs can't read them. The absolute AT500 / AT715 scales use a proprietary serial protocol that isn't supported by TouchDRO — or, as far as we know, other aftermarket DROs.

What resolution will I get from a sin/cos scale with TouchDRO?

TouchDRO reads sin/cos scales through a 1:1 zero-crossing comparator, which yields four counts per grating period. The effective resolution comes out to one-quarter of the scale's native grating pitch — so a 20 µm sin/cos scale gives an effective resolution of 5 µm.

What should I do with scale wires that don't map to a TouchDRO input pin?

Leave them unconnected, but isolate each bare end individually with heat-shrink or tape. An unterminated wire that shorts against another pin or the connector housing can damage the scale, so don't just leave them loose inside the shell.