Connecting DRO Scales to TouchDRO

Wiring a TouchDRO setup comes down to three connections: each scale plugs into a labeled input on the adapter, the adapter gets power over its USB cable, and the tablet talks to the adapter over Bluetooth, with no wire at all. This page covers the first two. If your scales came from our "Recommended DRO Scales" list or with a matching pinout chosen at checkout, the whole job is plugging in connectors.

This is the detail page for Step 3 of the "TouchDRO Quick Start Guide". The Bluetooth side of the setup is covered there in Step 5.

Which Scale Goes Where

The adapter has four scale inputs, one per axis: X, Y, Z, and W. Each input drives the matching readout on the screen, so the scale you plug into the X input becomes the X number in TouchDRO. There is no configuration involved in this mapping; it follows the labels.

Which machine axis belongs on which input follows the usual DRO conventions:

• Milling machine: table left-right on X, table in-out on Y, and the knee or spindle travel on Z. If the machine has both a knee scale and a quill scale, the quill goes on the W input, and TouchDRO can sum the two into one Z reading.
• Lathe: the cross slide on X and the carriage on Z. The Y input is left empty. Hiding the unused Y readout is a one-tap setting, covered in Step 4 of the "Quick Start Guide".

Plugging In Glass and Magnetic Scales

Glass and magnetic scales connect directly to the adapter's DB-9 scale inputs. The inputs are preconfigured for the scale pinout you chose when ordering the adapter, so a matching scale plugs straight in. Tighten the connector's retaining screws so vibration cannot work it loose over time.

A plug that does not fit, or scales you are not sure about, is a solved problem rather than a dead end:

• Scales with a different connector are handled with an adapter cable. The common ones are in the adapter cables collection.
• If the connector fits but the scale brand uses different pin functions, the adapter's inputs can be re-pinned by swapping the internal pin mapping boards. We exchange them for free; the "TDA Adapter Manual" lists the available pinout options.
• To check whether a specific brand or model works with TouchDRO at all, see "DRO Scale Compatibility".
• For no-name scales with no documentation, the "Identifying Unknown Scale Pinouts" guide shows how to work out the wiring safely before connecting anything.

Connecting Capacitive Scales

Capacitive scales (iGaging, Shahe, Mitutoyo SPC, and similar caliper-style scales, most often used on a quill or tailstock) speak a different electrical language than glass and magnetic scales, so they connect through a small converter rather than directly into a scale input. There is one converter per scale family: iGaging, Shahe, and Mitutoyo SPC. The converter plugs into the scale on one side and into an adapter input on the other.

Plugging in the converter is only half of the hookup. The adapter reads every input as a quadrature scale until you tell it otherwise, so the input the converter plugs into also needs its "Input Mode" set to the converter's protocol. That setting lives in the "Adapter Details" dialog and takes effect after an adapter restart. The "Serial Scales" section of the Quick Start Guide walks through it.

Tachometer and Touch Probe

The round auxiliary inputs are for the optional extras. Both adapters accept a spindle RPM sensor, and the TDA-420 also accepts up to two touch probes or a tool height setter. Neither is needed to get the DRO running; the wiring details, pinouts, and sensor requirements are in the "TDA Adapter Manual".

Powering the Adapter

The adapter is powered over USB from any common USB power source; a spare phone charger is the usual choice. Plug in the power last, after the scales are connected. The green "Power" light comes on at once, and about a second later the blue "Data" light gives three quick blinks and settles into one brief flash every two seconds, which means the adapter is running and waiting for the tablet. The "Status Lights" section of the adapter manual lists every pattern.

Power interruptions are not a problem for your work. The adapter records the scale positions when the power drops and restores them when it comes back, so an evening shutdown or a tripped breaker does not cost you your setup.

Checking Your Work

The wiring check happens on the tablet, once the app is installed and connected (Steps 4 and 5 of the "Quick Start Guide"). With the app showing green digits, crank each handle on the machine:

• Each handle should move its own readout. If a different readout moves, swap the two scale plugs at the adapter.
• If a readout counts in the wrong direction, no rewiring is needed; the axis direction setting in "Initial Configuration" flips it.
• If a readout stays gray while the others turn green, that input is not receiving a signal. Reseat the scale's connector, and if that does not cure it, see below.

Next: Step 4 of the "Quick Start Guide", putting TouchDRO on the tablet.