901MB / 902MB / 903MB

Multi-Channel Modbus-RTU Discrete I/O Modules

Product Features

  • Standard Modbus RTU protocol with high-speed RS-485 communication (up to 115K bps)
  • Twelve I/O channels in a single inch-wide unit reduces system costs and saves panel space
  • High-voltage, high-current, open-drain outputs enable direct (low-side) control of external devices
  • High-voltage buffered inputs monitor discrete levels from a variety of industrial devices
  • Tandem input/output circuitry (903 models only) connects input buffers with open-drain outputs for convenient loopback monitoring of the output state
  • Outputs have built-in over-temperature and over-current shut-down protection, plus active clamping circuits for switching inductive loads
  • Watchdog timers provide a configurable failsafe output state for use when host I/O communication is lost
  • Three-way isolation eliminates potential ground loops between power, I/O, and network circuitry
  • Self-diagnostics monitor microcontroller activity to detect operational failures (lock-up) and execute a reset to restore communication
  • Operating temperature: -25°C to +70°C (-13°F to +158°F).

These modules provide twelve discrete input and/or output channels. Isolation separates the I/O, power, and network circuits. Network communication adheres to the industry-standard RS-485 Modbus RTU protocol. Both AC and DC power sources are supported with wide range, nonpolarized, diode-coupled terminals.


  • Datasheet for 901MB / 902MB / 903MB

Ordering info

Available Models

Model No.Model Description
901MB-0900Modbus RTU Discrete Input Module: 12 input channels
902MB-0900Modbus RTU Discrete Output Module: 12 output channels
903MB-0900Modbus RTU Discrete Input/Output Module: 12 input & 12 output channels.
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