Frequency/Pulse Counter Modbus Input Modules 942MB

This signal conditioner is a two channel analog input module with discrete outputs plus Modbus communication. It conditions periodic or pulse waveform inputs and provides solid state relays for limit alarms or ON/OFF control.

The Acromag 942MB are Frequency/Pulse Counter Modbus-RTU Input Modules with periodic or pulse waveform input.

Firstly, the 942MB has two input channels with 0 to 50kHz in 3 selectable ranges. With amplitudes up to 140V AC peak and 200V peak. As well as pulse counter range of 0 to 65535. These versatile inputs accommodate many applications using TTL, magnetic pickups, proximity sensors or a variety of switches. Such as high/low side transistor, dry contact, open drain and open connector.

The bipolar and unipolar waveforms are supported with a selectable input bias that accepts both zero and non zero crossing signals. Voltage threshold and relative hysteresis are user selectable. Inputs can function as event counters with separate microcontrollers for each channels. Module counts pulses on the positive or negative edge and wrap around to zero for continuous counting. Software controls enable remote resets.

Finally, Modules used in On/Off applications.

Features of the Frequency/Pulse Counter Modbus-RTU Input Modules 942MB include:

  • Standard Modbus RTU protocol with high-speed RS-485 communication (up to 115K bps)
  • Separate microcontrollers on each channel for pulse counting and period measurement
  • Solid-state relay outputs enable local limit alarms or host-controlled on/off switching
  • As well as bipolar and unipolar input signal support
  • Programmable pulse counter functions
  • Input filtering functions include hysteresis, averaging, debounce, relay time delay, and alarm deadband controls
  • Also 4-way isolation (input, output, power, network)
  • Watchdog timers provide a failsafe output
  • 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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