Gyrocompass ER-MNS-08

Introduction
The ER-MNS-08 single‑axis MEMS North Seeker is an integrated mechatronic system for rapid autonomous determination of true north. It combines a navigation‑grade MEMS gyroscope, accelerometer, mechanical rotation control and an embedded processor to compute heading by measuring the Earth's rotation rate.

Key Features

• North‑seeking accuracy down to 0.25° secψ (ER-MNS-08C)
• Attitude measurement range: −30° to +30°
• Fast north‑seeking: typical completion within 180 s
• Independent operation: no external signals required; immune to local magnetic disturbances
• Compact and lightweight: 80×85×72.5 mm; weight ≤700 g

Applications

• Guidance for intelligent tunneling and coal mine roadways
• Directional drilling and other borehole trajectory control
• Integration with engineering equipment (directional drilling rigs, bridge erection machines, etc.)
• Emergency response and field operations requiring rapid true‑north determination

Specifications (summary)
Model: ER-MNS-08A / ER-MNS-08B / ER-MNS-08C
North‑seeking accuracy: 1° secψ (08A); 0.5° secψ (08B); 0.25° secψ (08C)
Attitude accuracy (1σ): 0.5°
North‑seeking time: 180 s
North‑seeking range: 0°–360°
Attitude measurement range: −30°–+30°
Working temperature: 5°C to +55°C
Power supply: DC 24 V
Output interface: RS422
Dimensions (mm): 80 × 85 × 72.5
Weight: ≤700 g

Wiring definition (J30J-15)
Pin No. 1: VCC — 24 VDC
Pin No. 2: / (reserved)
Pin No. 3: GND
Pin No. 4–5: / (reserved)
Pin No. 6: RS422, TX+
Pin No. 7: RS422, TX-
Pin No. 8: RS422, RXD+
Pin No. 9: RS422, RXD-
Pin No. 10–15: / (reserved)

Communication protocol — Receiving data (frame definition and data map)
Frame header (FH): 0x55, 0xAA (2 bytes)
Protocol version: 0x01 (1 byte)
Frame number: unsigned int, 4 bytes (increment per packet)
Reserved: 1 byte
Pitch angle: Float, 4 bytes (bytes 8–11), unit: degrees; stored value ×0.01 = degrees
Roll angle: Float, 4 bytes (bytes 12–15), unit: degrees; stored value ×0.01 = degrees
Heading angle: Float, 4 bytes (bytes 16–19), unit: degrees; stored value ×0.01 = degrees
Main gyro: Float, 4 bytes (bytes 20–23), unit: °/s; divide stored value by 18000
X accel: Int, 4 bytes (bytes 24–27), unit: m/s²; divide by 1,000,000
Y accel: Int, 4 bytes (bytes 28–31), unit: m/s²; divide by 1,000,000
Z accel: Int, 4 bytes (bytes 32–35), unit: m/s²; divide by 1,000,000
Reserved: 1 byte
Temperature: Float, 4 bytes (bytes 48–51), unit: °C
Checksum: XOR of bytes 4 through 19 (as defined in protocol)

Communication protocol — Sending data (control & commands)
Control frame example (start / restart / send coordinates): sequence includes bytes such as 0xEB, 0x80, 0x00, control_flag (0xCC = restart; 0xAA = send lon/lat/alt), followed by payload, tail bytes 0xAA,0xBB,0xCC,0xDD and XOR check.
To send longitude/latitude/altitude: pack Longitude and Latitude as 4‑byte integers = floating degrees × 1e6; Altitude as 4‑byte int (meters). Example transmission order: bytes 5–8 Latitude (Lat × 1e6), bytes 9–12 Longitude (Lon × 1e6), bytes 13–16 Altitude (m). Tail and XOR follow as defined.

Maintenance and usage
If no serial output is observed, verify physical connections, serial port settings and data format. If correct and output remains absent, consult qualified service. Handle unit carefully during transport/installation to avoid shocks. During north‑seeking the carrier must remain absolutely stationary to ensure accuracy.

Technical specifications

• Model: ER-MNS-08 (variants: 08A / 08B / 08C)
• North‑seeking accuracy: up to 0.25° secψ (ER-MNS-08C)
• Attitude accuracy (1σ): 0.5°
• North‑seeking time: 180 s
• Attitude range: −30° to +30°
• North‑seeking range: 0° to 360°
• Operating temperature: 5°C to +55°C
• Power: DC 24 V
• Interface: RS422
• Dimensions: 80 × 85 × 72.5 mm
• Weight: ≤700 g