Video Signal Converters in CNC Control Systems
Keywords: video signal converter, CNC control system, signal conversion, industrial automation
Target Audience: CNC engineers, equipment maintenance personnel, industrial control system integrators
1. Why CNC Systems Need Video Signal Converters
Many CNC machine tools in service today were designed with display interfaces that are incompatible with modern LCD monitors. The primary scenarios requiring signal conversion include:
- CGA/EGA to VGA: Legacy CNC controllers output CGA (15kHz) or EGA (22kHz) signals that cannot directly drive VGA LCD displays
- Composite sync to separate H/V sync: Some systems output RGBS (composite sync) which must be separated into RGBHV for VGA displays
- Scan rate conversion: Converting low scan rate signals to standard VGA timing (31.5kHz+)
- Digital-to-analog conversion: TTL-level digital signals must be converted to analog VGA signals
2. Signal Types in CNC Systems
| Signal Type | Frequency | Voltage Level | Connector | FANUC Systems |
|---|---|---|---|---|
| CGA (TTL) | 15.75 kHz H / 60 Hz V | Digital 0/5V | 9-pin D-Sub | FANUC 0-M, 0-T (very early) |
| EGA (TTL) | 21.85 kHz H / 60 Hz V | Digital 0/5V | 9-pin D-Sub | FANUC 0-TC, 0-MC |
| RGBS (Analog) | 15-24 kHz H / 50-60 Hz V | Analog 0.7Vpp + Composite Sync | BNC or HONDA | FANUC 16i, 18i (some models) |
| RGBHV/VGA (Analog) | 31.5-48 kHz H / 60-75 Hz V | Analog 0.7Vpp + Separate Sync | HONDA 20-pin / HD15 | FANUC 0i, 16i, 18i |
3. Converter Selection Criteria
3.1 Input/Output Compatibility
| Selection Factor | Requirement | Verification Method |
|---|---|---|
| Input signal type | Must match CNC controller output | Check controller documentation or measure with oscilloscope |
| Output resolution | Must match LCD display native resolution | Check LCD specifications |
| Refresh rate | 60 Hz minimum, compatible with CNC frame rate | Verify in FANUC system parameters |
| Scan rate handling | Line doubling for CGA/EGA input | Verify with test pattern display |
3.2 Environmental Requirements
- Operating temperature: -20°C to +70°C for workshop environments
- Power supply: 12-36 VDC wide voltage range for PLC/cabinet compatibility
- EMC compliance: IEC/EN 61326-1 Class 2 for industrial environments
- Vibration resistance: IEC 60068-2-6 for machine tool environments
- MTBF: ≥ 50,000 hours for 24/7 operation
4. Installation Best Practices
- Pre-installation: Document all existing cable connections and system parameters before making any changes
- Power isolation: Always power down the CNC machine before connecting or disconnecting display cables
- Cable routing: Route signal cables away from motor power cables and servo drives to minimize EMI
- Grounding: Ensure proper grounding of the converter to prevent ground loops and signal noise
- Vibration mounting: Secure the converter with vibration-dampening mounts inside the electrical cabinet
- Labeling: Label all connections and document the converter model and settings for future maintenance
5. Kongto Technology Converter Product Line
| Model | Input | Output | Key Features | Price |
|---|---|---|---|---|
| JTX-CVR-001 | CGA (15kHz) | VGA (31kHz) | Auto line-doubling, plug-and-play | CNY 850 |
| JTX-CVR-002 | EGA (22kHz) | VGA (31kHz) | Auto line-doubling, wide voltage | CNY 880 |
| JTX-CVR-003 | RGBS | RGBHV/VGA | Sync separator, adjustable position | CNY 750 |
| JTX-CVR-004 | CGA+EGA (dual) | VGA | Auto-detect input type | CNY 950 |
| JTX-CVR-005 | TTL RGB | VGA | 6-bit DAC, supports 64 colors | CNY 720 |
All models feature: -20°C to +70°C operating range, 12-36 VDC power, MTBF ≥ 50,000 hours, CE/UL certified.
Contact Kongto Technology at szkongto01@foxmail.com for technical consultation.