The Measurement Computing CIO-EXP32 is a 32-channel analog multiplexer board that expands the input capacity of compatible DAQ systems by routing up to 32 differential signal sources into a single analog input channel. Designed for Measurement Computing DAS08 and DAS16 series boards, this module organizes its inputs into two independent 16-channel banks with switch-selectable gain and integrated cold junction compensation for thermocouple measurements.
Technical Specifications
Channel Architecture
• 32 differential inputs organized as two banks of 16 channels
• Single-ended multiplexed output; secondary channel for CJC signal
• ±10 V input range across all channels
• ±10 V common mode range
Gain & Linearity
• Switch-selectable gains: ×1, ×10, ×100, ×200, ×500
• Gain error: 0.002% typical / 0.02% max (×1) to 0.05% typical / 0.5% max (×500)
• Non-linearity: 0.0005% typical / 0.005% max (×1) to 0.005% typical / 0.02% max (×500)
• Temperature coefficient: ±20 ppm/°C (×1, ×10) to ±100 ppm/°C (×500)
• Offset drift: ±15 µV/°C
Input Characteristics
• Input impedance: >100 MΩ min (high-Z config); >100 kΩ min (grounded config)
• Input leakage current: 2 nA typical, 6 nA max
• CMRR: >90 dB at 60 Hz
• Absolute maximum input: ±35 V (power on), ±20 V (power off)
Signal Conditioning
• Selectable 7 Hz input filter (solder bridge configurable)
• Open thermocouple detection at -50 mV (selectable via solder bridge)
• 100 kΩ input ground reference (selectable via solder bridge)
Cold Junction Compensation
• Onboard semiconductor CJC sensor: 24 mV/°C output
• Zero crossing at 0 °C
• One adjustment potentiometer per board
– Key Features
• Four digital control inputs for channel selection via host DAQ board outputs
• Per-bank gain switching for flexible signal conditioning
• Solder bridge configuration for filter, thermocouple detection, and ground reference
• Tight gain error and non-linearity across the gain range
– Typical Applications
Multichannel thermocouple monitoring, low-level signal acquisition, differential sensor arrays, and test systems requiring expanded analog input density without additional DAQ hardware.
– Compatibility & Integration
Primary compatibility with DAS08 and DAS16 series boards; interfaces with other DAQ devices supporting external analog multiplexing.
