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DI-932MB and DI-934MB - OBSOLETE

DI-900 Modbus Distributed Data AcquisitionRTD/Resistance Input Modules
RTD or Resistance Input
Limit Alarms or Discrete Outputs

  • Standard Modbus RTU protocol with high-speed RS-485 communication (up to 115K bps)
  • 16-bit sigma-delta A/D yields 0.1°C resolution and 0.25°C accuracy (Pt, Ni RTDs)
  • RTD linearization and sensor break detection ensure reliable measurements
  • Discrete relay outputs enable local temperature limit alarms or host-controlled on/off switching
  • Heavy-duty 1A solid-state relays provide dependable on/off control of industrial devices
  • Self-calibration lowers maintenance costs by reducing periodic manual calibration checks
  • Watchdog timers provide a configurable failsafe output state for use when host I/O communication is lost
  • Four-way isolation eliminates potential ground loops between power, input, output and network circuitry
  • Self-diagnostics monitor microcontroller activity to detect operational failures (lock-up) and execute a reset to restore communication.

Data Sheet


Product Highlights

This signal conditioner is a dual or quad-channel analog input module with one discrete/relay output per input channel and a Modbus interface. It filters and linearizes RTD or resistance inputs while providing isolation between input, output, power, and network circuits. Lead wire compensation and pscale/downscale sensor break detection are standard. Low voltage AC and DC power sources are supported with nonpolarized, diode-coupled terminals.

The programmable inputs accommodate four RTD types plus wide-range resistance signals. Flexible discrete outputs operate as alarms or on/off controllers. As limit alarms, each discrete output can be configured with high and/or low setpoints exclusively tied to an analog input channel. Alarm trips function without host communication enabling low-cost stand-alone alarms as well as local backup for the primary control system. Otherwise, on/off control is based on commands issued by the host system. See the Circuit Connection Diagrams.

Combining flexible transmitter functions, mixed signal I/O, alarm support, and a network interface in a single package, makes this instrument extremely powerful. Multi-channel design adds cost-efficiency and allows high-density mounting. Plus, safe, rugged construction makes these modules reliable for use in both control room and distributed field I/O applications. Custom module configurations are also possible (consult factory for details).

Everything you need to complete your network is available from DATAQ Instruments, Inc. - isolators, signal converters, signal boosters, power sources, and mounting hardware. Check out the Accessories.