Modbus-RTU Discrete I/O Modules 904MB 905MB 906MB

These modules provide 12 discrete input and/or output channels. They contain isolation which separates the I/O, power and network circuits. Network communication follows the industry standard RS-485 Modbus-RTU protocol. They have are considered high side switching with active high inputs and sourcing outputs.

The difference in the models are: 904MB contains 12 input channels, 905MB has 12 output channels and 906MB has 12 input or output channels.

The Acromag 904MB, 905MB and 906MB are Modbus-RTU Discrete I/O Modules.

Firstly, the outputs are for current sourcing or high side switching applications. The buffered inputs are active high. Which means they complement models 901, 902 and 903. As these units have low side output switches and active low inputs. The socketed pull down resistors are removable or swappable depending on your application requirements.

The 906MB model has 12 input/output points and may be used as either on a bit by bit basis. Outputs read back to verify output settings. With a multichannel design in a rugged case makes this the perfect reliable module for control room and distributed field I/O applications.

Features of the Modbus-RTU Discrete I/O Modules 904MB 905MB 906MB include:

  • 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-source outputs enable direct (high-side) control of external devices
  • High-voltage buffered inputs monitor discrete levels from a variety of industrial devices
  • Tandem input/output circuitry (906 models only) connects input buffers with open-source outputs for convenient loopback monitoring of the output state
  • Watchdog timers provide a configurable fail-safe 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


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