Mitutoyo Digimatic/SPC Pinouts
Mitutoyo's Digimatic protocol is used in digital calipers, height gauges, and some linear scales. This guide covers the standard pinouts and protocol specifications.
Standard 4-Pin Digimatic Connector
The most common Digimatic connector used on calipers and portable tools:
| Pin | Signal | Description | Voltage |
|---|---|---|---|
| 1 | GND | Ground/0V reference | 0V |
| 2 | CLOCK | Clock signal | 0-1.5V |
| 3 | DATA | Serial data | 0-1.5V |
| 4 | VCC | Power supply | +1.5V |
6-Pin SPC Connector
Used on some Digimatic indicators and specialized tools:
| Pin | Signal | Description | Voltage |
|---|---|---|---|
| 1 | GND | Ground/0V reference | 0V |
| 2 | CLOCK | Clock signal | 0-1.5V |
| 3 | DATA | Serial data | 0-1.5V |
| 4 | VCC | Power supply | +1.5V |
| 5 | REQ | Request/enable signal | 0-1.5V |
| 6 | READY | Ready/status signal | 0-1.5V |
Protocol Specifications
Data Format
- Total bits: 52 bits per transmission
- Clock frequency: Approximately 300Hz
- Data transmission: Serial, MSB first
- Update rate: Typically 2-5 Hz
Data Packet Structure
- Bits 1-4: Start bits (always 1111)
- Bits 5-44: BCD encoded measurement data
- Bit 45: Sign bit (0 = positive, 1 = negative)
- Bits 46-49: Decimal point position
- Bits 50-52: Units and status flags
Compatible Devices
Digital Calipers
- Mitutoyo Absolute Digimatic calipers
- Mitutoyo Coolant Proof calipers
- Various Mitutoyo caliper series with data output
Height Gauges
- Mitutoyo Digital Height Gauges
- Digimatic height gauge accessories
Indicators and Gauges
- Digimatic indicators
- Digital depth gauges
- Specialized measurement tools with SPC output
TouchDRO Compatibility
TDA-4xx Series
- Full support: Native Digimatic protocol support
- Auto-detection: Automatically recognizes Digimatic devices
- Configuration: Minimal setup required
DIY Adapters
- Limited support: Requires specific firmware
- Voltage levels: May need level conversion (1.5V to 3.3V/5V)
- Protocol handling: Requires software implementation
Voltage Considerations
Standard Digimatic (1.5V)
- Most Mitutoyo devices use 1.5V logic levels
- Requires level conversion for 3.3V/5V systems
- Low power consumption
Level Conversion
- Use voltage dividers or level shifters
- Ensure proper signal integrity
- Consider using dedicated interface chips
Wiring Examples
Direct Connection to TDA-4xx
- Pin 1 (GND) → Adapter GND
- Pin 2 (CLOCK) → Adapter CLK input
- Pin 3 (DATA) → Adapter DATA input
- Pin 4 (VCC) → Adapter +1.5V supply
DIY Adapter with Level Conversion
- Add voltage dividers or level shifters
- Use pull-up resistors on clock and data lines
- Ensure proper grounding
Cable Specifications
- Length: Keep under 3 meters for reliable operation
- Shielding: Use shielded cable for longer runs
- Connectors: Use proper Digimatic connectors when possible
- Wire gauge: 24-28 AWG suitable for most applications
Troubleshooting
No Data Reception
- Check power supply voltage (should be 1.5V)
- Verify clock and data line connections
- Ensure device is not in sleep mode
- Check for proper grounding
Garbled Data
- Verify voltage levels and level conversion
- Check for noise on signal lines
- Ensure proper cable shielding
- Verify protocol timing
Intermittent Operation
- Check for loose connections
- Verify power supply stability
- Device may be entering sleep mode
- Check cable integrity
Power Management
- Many Digimatic devices have sleep modes
- Some require periodic "wake up" signals
- Battery-powered devices may shut down automatically
- Consider external power supplies for continuous operation