The NI TBX-68S is an isothermal terminal block designed for thermocouple measurements with National Instruments PXI switch cards. It provides 68 screw terminals on a shielded board and incorporates a high-accuracy thermistor for cold-junction temperature compensation, enabling precise temperature data acquisition across a wide measurement range.
Technical Specifications
Terminal Configuration
• 68 screw terminals for signal connections
• Shielded board construction
• Supports thermocouples, thermistors, RTDs, and voltage signals
• Auto-zeroing circuitry supported
• Maximum input voltage: 30 Vrms / 42 Vpk / 60 VDC
Cold-Junction Temperature Sensor
• High-accuracy thermistor with integrated output
• Accuracy: ±0.5°C (15°C to 35°C); ±0.9°C (0°C to 15°C and 35°C to 55°C)
• Repeatability: 0.2°C (15°C to 35°C)
• Resistance range: 16,305 Ω to 1,492 Ω (0°C to 55°C)
• Output voltage: 198.54 mV at 0°C to 19.58 mV at 55°C
Physical
• Dimensions: 12.7 × 11.2 × 7.62 cm (5.0 × 4.4 × 3.0 in.)
• Enclosure designed to minimize air currents and maintain isothermal environment
– Key Features
• Isothermal construction minimizes temperature gradients across terminal connections
• DIN-rail mountable (DIN EN 50 022, DIN EN 50 03 compatible)
• Compatible with NI TBX Rack-Mount Assembly
• Direct front-panel connection to NI-2501 and NI-2503 PXI switch cards
• Shielded and unshielded cable options available
– Typical Applications
Thermocouple signal conditioning and measurement in industrial process control, laboratory automation, and PXI-based data acquisition systems requiring cold-junction compensation.
– Compatibility & Integration
PXI Switch Cards: NI-2501, NI-2503
Compatible Cabling: SH68-68S shielded cable (1 m, 2 m, or 5 m); R6868 ribbon cable
Mounting: Standard European DIN EN rails
