The Acu‑Rite MillMate is a two‑axis digital readout (DRO) system used to provide linear position feedback on milling machines. Common faults include incorrect scale calibration or resolution settings that cause the displayed distance to be half of the actual travel, as well as connector or wiring issues on the DSUB9 interface that can lead to intermittent or zero readings. For this class of DROs, power‑supply voltage drops, loose ground connections, and firmware version mismatches are frequent failure points. First‑check diagnostics: verify 12 V DC supply continuity and correct voltage at the DRO input; inspect all DSUB9 pins for proper solder joints and secure connectors; review the DRO’s configuration parameters (scale resolution) against the manual to ensure they match the installed scale kit.[oss-gpt-20b]