SDM-IO16A 16 Channel Input/Output Expansion Module

The SDM-IO16A expands the digital input and/or output capability of Campbell Scientific dataloggers.

It offers similar functionality to the control ports of the datalogger. The SDM-IO16A was designed to replace the SDM-IO16. It is more compact in comparison and has gas-discharge tubes fitted on all inputs for improved surge protection. It is fully software-compatible but also includes an option to run in a special high-speed mode that allows pulse measurements up to 8 kHz on all channels and four times more resolution on some timing measurements.


  • Provides 16 digital I/O ports
  • Input configuration options: Monitor logic state, count pulses, measure signal frequency, and determine duty cycle
  • Output configuration options: Port set to 0 or 5 V by datalogger or source current up to 100 mA
  • When driving loads, external power supply recommended
  • I/O lines protected against high-level surges with gas discharge tubes



  • Operating voltage: 9 to 18 Vdc
  • Current drain: 600 microamps typical standby (all ports high, no load, excludes pulse counting)
  • 3 milliamps maximum (active will all 16 port counting pulses at 2 kHz and no output load)


  • Voltage (no load): ON/HI - nominal 5 V, minimum 4.5 V; OFF/LO - nominal 0 V, maximum 0.1 V
  • Source current: output will source 42 mA@ 3 V; 133 mA short-circuited to ground


  • Voltage: High - 4.0 v minimum threshold, Low - 1.0 V maximum threshold


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