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Product short description:
  • 2 input channels, 0 to 50KHz in 3 selectable ranges: Amplitudes up to 140V AC peak, Amplitudes up to 200V peak, Pulse counter range of 0 to 65535
  • Solid-state discrete output relays (1A DC loads), 0 to 48V DC
  • 10 to 36V DC, 24V AC power
  • Modbus-RTU high-speed RS-485

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

942MB: Frequency/Pulse Counter Modbus-RTU Input Modules with Periodic or Pulse Waveform Input Description

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

Versatile inputs accommodate many applications using TTL, magnetic pickups, proximity sensors, or a variety of switches (high/low-side transistor, dry contact, open drain, open collector). 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 also user selectable.

Inputs may also function as event counters with separate microcontrollers for each channel. The module counts pulses on the positive or negative edge. It can wrap around to zero for continuous
counting, latch at a programmed count value (setpoint), or automatically reset itself to zero after reaching a setpoint value. Software controls enable remote resets. A variety of filters help
remove noise, jitter, and other mechanical effects to prevent false counts.

The discrete outputs can operate as independent alarms or provide on/off control regulated by the host system. As limit alarms, each output can be set for high and/or low setpoints exclusively tied to an analog input. These low cost modules are ideal for standalone alarms as well as for local backup of the primary control system.

Periodic or Pulse Waveform Input
Limit Alarms or Discrete Outputs

Model: 942MB: 2 input channels.

Input
Two input channels: 0 to 50KHz in three selectable ranges; Amplitudes up to 140V AC or 200V peak, Pulse counter range of 0 to 65535.

Output
Two output channels: Solid-state relays (1A DC loads), 0 to 48V DC.

Network Communication: Modbus-RTU high-speed RS-485.

Power Requirement: 10 to 36V DC, 24V AC.

Approvals: CE marked. UL, cUL listed Class I; Division 2; Groups A, B, C, D.

Performance Specifications

Frequency/Counter Input

Input Ranges: Input type user-configured. Applies to both channels.

Input Range             Accuracy     Accuracy over Temp.
0 to 100Hz                   ±0.04Hz                   ±0.06Hz
0 to 1000Hz                 ±0.4Hz                      ±0.6Hz
0 to 50,000Hz             ±10Hz                       ±15Hz
0 to 65,535 pulses    ±1 pulse                   ±1 pulse

Unipolar Input Configuration: Amplitude: 0 to 3V minimum range, 0 to 200V peak maximum range.
Threshold: Configurable for 1.5V or 5V, typical.
Hysteresis: Configurable for ±25mV (at 1.5V threshold), or ±83mV (at 5.0V threshold), typical.

Bipolar (Zero-Crossing) Input Configuration
Amplitude (0-20KHz): ±50mV minimum (with ±25mV hysteresis), or ±150mV minimum (with ±83mV hysteresis), to ±200V peak maximum.
Amplitude (Above 20KHz): ±100mV minimum (with ±25mV hysteresis), or ±200mV minimum (with ±83mV hysteresis), to ±200V peak maximum.
Threshold: 0mV nominal, 0.01V typical with ±25mV hysteresis; 0.03V typical with ±83mV hysteresis.
Hysteresis: Configurable for ±25mV or ±83mV, typical.

Resolution
0 to 100Hz input range: 0.01Hz.
0 to 1000Hz input range: 0.1Hz.
0 to 50,000Hz input range: 1Hz.
Pulse counter: 1 pulse.

Minimum Input Pulse Width: 10μS (frequency input); 5mS (pulse input).

Counting Rate: 100Hz maximum counting rate (5mS ON and 5mS OFF for 10mS period or 100Hz).

Input Impedance: 35K ohms, typical.

Input Filter Bandwidth: -3dB at 35kHz, typical.

Input Pullup/Pulldown: Software selectable 2.7K ohm input pullup to +5V and a 1K ohm input pulldown to return. The resistors may also be left floating (none).

Input Debounce: 0 to 1.375 seconds, configurable in 5mS increments.

Noise Rejection: Common mode: 80dB @ 60Hz, typical with 100 ohm input unbalance.

Discrete Output

Output Type: Solid-State Relay (SSR), one Form A (SPST-NO) switch per input channel. Outputs share a common return connection at the RTN terminals for low-side switching.

Output Voltage Range: 0 to 48V DC, 1A DC.

Output ON Resistance: 0.4 ohms maximum.

Output Response Time: 4.1ms typical, from receipt of command to gate transition of the output MOSFET.

Operation: Digital outputs are set to their OFF state following a software or power-on reset. Outputs can be set to user-defined states following a watchdog timeout.

Communication

Supported Modbus Commands: The command/response protocol for communicating with this module adheres to the Modbus/RTU standard for the following Modbus functions:

  • Read Holding Registers
  • Read Coil
  • Read Input Registers
  • Reset Slave
  • Preset Single Register
  • Report Slave ID
  • Force Multiple Coils
  • Force Single Coil
  • Preset Multiple Registers

LED Indicators: LEDs indicate power, status, and discrete level/alarm.

Power and Isolation

Power Requirements
10 to 36V DC.
22 to 26V AC.

Isolation
1500V AC for 60 seconds or 250V AC continuous.
4-way isolation between input, network, power and discrete I/O circuits. Inputs are isolated channel-to channel for common mode voltage to ±5V DC.

  • 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
  • Bipolar and unipolar input signal support
  • Programmable pulse counter functions
  • Input filtering functions include hysteresis, averaging, debounce, relay time delay, and alarm deadband controls
  • 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 (-13°F to 158°F)

 

 

What is Modbus/RS485? An Introduction - 8500648 (Log in to view the file)
Modbus/RS485 Network an Introduction White Paper This white paper describes the operation of Modbus as it relates to Acromag Series 900MB I/O modules.   Learn more: What is Ethernet/IP?
How to Configure Kepware KEPServerEX 5.0 for Communications with Modbus I/O Modules - 8500880
Configuring Kepware KEPServerEX 5.0 for Communications with Acromag BusWorks Modbus I/O Modules Introduction This document provides example steps for configuring the Kepware KEPServerEX OPC Server for communications with Acromag Busworks Modbus RTU and Modbus TCP/IP Distributed I/O Modules. Once the server is configured, data may be read from or written to the I/O module using...
How to Configure LabVIEW to Communicate with Modbus I/O Modules Via an OPC Server - 8500881
Configuring LabVIEW 2009 to Communicate with Acromag BusWorks and EtherStax Modbus I/O Modules via an OPC Server Introduction National Instruments™ LabVIEW can be used to monitor and control Acromag BusWorks ® and EtherStax ® Modbus I/O modules via an OPC server. A separate application note, Configuring Kepware KEPServerEX® 5.0 for communications with Acromag BusWorks and EtherStax...

Manuals

942MB User Manual (Log in to download the file)

How to Use SIIG USB-to-Serial Cable With Windows Tech Note (Log in to download the file)

900C-SIP: Modbus RTU Configuration Software Information Page (Log in to download the file)
  • Compare

    5034-202: RS-485 to 3-wire Cable Converter and Cable

    RS-485 to 3-wire cable converter and cable, DB-9M to 3 x 12AWG RS-485 cable, 8 ft.
    Select options
  • Compare

    5034-214: RS232 to RS485 Serial Port Converter

    Non-isolated RS232-to-RS485 serial port converter, RS232 port-powered, DB-9F to DB-9F.
    Select options
  • Compare

    900C-SIP: Configuration Software Interface Package

    • Configuration Software
    • USB-to-RS232 Adapter
    • RS232-to-RS485 Adapter
    • Interface Cable
     
    Select options

Additional information

Weight 16 oz
Dimensions 1.5 × 5.5 × 4.5 in
Part Number

942MB-0900: 2 input channels

Configuration

Windows Software Configuration

Communication

Modbus-RTU, RS422/485

Product Series

BusWorks 900MB

  • Description

    942MB: Frequency/Pulse Counter Modbus-RTU Input Modules with Periodic or Pulse Waveform Input Description

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

    Versatile inputs accommodate many applications using TTL, magnetic pickups, proximity sensors, or a variety of switches (high/low-side transistor, dry contact, open drain, open collector). 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 also user selectable.

    Inputs may also function as event counters with separate microcontrollers for each channel. The module counts pulses on the positive or negative edge. It can wrap around to zero for continuous
    counting, latch at a programmed count value (setpoint), or automatically reset itself to zero after reaching a setpoint value. Software controls enable remote resets. A variety of filters help
    remove noise, jitter, and other mechanical effects to prevent false counts.

    The discrete outputs can operate as independent alarms or provide on/off control regulated by the host system. As limit alarms, each output can be set for high and/or low setpoints exclusively tied to an analog input. These low cost modules are ideal for standalone alarms as well as for local backup of the primary control system.

    Periodic or Pulse Waveform Input
    Limit Alarms or Discrete Outputs

    Model: 942MB: 2 input channels.

    Input
    Two input channels: 0 to 50KHz in three selectable ranges; Amplitudes up to 140V AC or 200V peak, Pulse counter range of 0 to 65535.

    Output
    Two output channels: Solid-state relays (1A DC loads), 0 to 48V DC.

    Network Communication: Modbus-RTU high-speed RS-485.

    Power Requirement: 10 to 36V DC, 24V AC.

    Approvals: CE marked. UL, cUL listed Class I; Division 2; Groups A, B, C, D.

    Performance Specifications

    Frequency/Counter Input

    Input Ranges: Input type user-configured. Applies to both channels.

    Input Range             Accuracy     Accuracy over Temp.
    0 to 100Hz                   ±0.04Hz                   ±0.06Hz
    0 to 1000Hz                 ±0.4Hz                      ±0.6Hz
    0 to 50,000Hz             ±10Hz                       ±15Hz
    0 to 65,535 pulses    ±1 pulse                   ±1 pulse

    Unipolar Input Configuration: Amplitude: 0 to 3V minimum range, 0 to 200V peak maximum range.
    Threshold: Configurable for 1.5V or 5V, typical.
    Hysteresis: Configurable for ±25mV (at 1.5V threshold), or ±83mV (at 5.0V threshold), typical.

    Bipolar (Zero-Crossing) Input Configuration
    Amplitude (0-20KHz): ±50mV minimum (with ±25mV hysteresis), or ±150mV minimum (with ±83mV hysteresis), to ±200V peak maximum.
    Amplitude (Above 20KHz): ±100mV minimum (with ±25mV hysteresis), or ±200mV minimum (with ±83mV hysteresis), to ±200V peak maximum.
    Threshold: 0mV nominal, 0.01V typical with ±25mV hysteresis; 0.03V typical with ±83mV hysteresis.
    Hysteresis: Configurable for ±25mV or ±83mV, typical.

    Resolution
    0 to 100Hz input range: 0.01Hz.
    0 to 1000Hz input range: 0.1Hz.
    0 to 50,000Hz input range: 1Hz.
    Pulse counter: 1 pulse.

    Minimum Input Pulse Width: 10μS (frequency input); 5mS (pulse input).

    Counting Rate: 100Hz maximum counting rate (5mS ON and 5mS OFF for 10mS period or 100Hz).

    Input Impedance: 35K ohms, typical.

    Input Filter Bandwidth: -3dB at 35kHz, typical.

    Input Pullup/Pulldown: Software selectable 2.7K ohm input pullup to +5V and a 1K ohm input pulldown to return. The resistors may also be left floating (none).

    Input Debounce: 0 to 1.375 seconds, configurable in 5mS increments.

    Noise Rejection: Common mode: 80dB @ 60Hz, typical with 100 ohm input unbalance.

    Discrete Output

    Output Type: Solid-State Relay (SSR), one Form A (SPST-NO) switch per input channel. Outputs share a common return connection at the RTN terminals for low-side switching.

    Output Voltage Range: 0 to 48V DC, 1A DC.

    Output ON Resistance: 0.4 ohms maximum.

    Output Response Time: 4.1ms typical, from receipt of command to gate transition of the output MOSFET.

    Operation: Digital outputs are set to their OFF state following a software or power-on reset. Outputs can be set to user-defined states following a watchdog timeout.

    Communication

    Supported Modbus Commands: The command/response protocol for communicating with this module adheres to the Modbus/RTU standard for the following Modbus functions:

    • Read Holding Registers
    • Read Coil
    • Read Input Registers
    • Reset Slave
    • Preset Single Register
    • Report Slave ID
    • Force Multiple Coils
    • Force Single Coil
    • Preset Multiple Registers

    LED Indicators: LEDs indicate power, status, and discrete level/alarm.

    Power and Isolation

    Power Requirements
    10 to 36V DC.
    22 to 26V AC.

    Isolation
    1500V AC for 60 seconds or 250V AC continuous.
    4-way isolation between input, network, power and discrete I/O circuits. Inputs are isolated channel-to channel for common mode voltage to ±5V DC.

  • Features & Benefits

    • 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
    • Bipolar and unipolar input signal support
    • Programmable pulse counter functions
    • Input filtering functions include hysteresis, averaging, debounce, relay time delay, and alarm deadband controls
    • 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 (-13°F to 158°F)

     

     

  • Tech Papers

    What is Modbus/RS485? An Introduction - 8500648 (Log in to view the file)
    Modbus/RS485 Network an Introduction White Paper This white paper describes the operation of Modbus as it relates to Acromag Series 900MB I/O modules.   Learn more: What is Ethernet/IP?
    How to Configure Kepware KEPServerEX 5.0 for Communications with Modbus I/O Modules - 8500880
    Configuring Kepware KEPServerEX 5.0 for Communications with Acromag BusWorks Modbus I/O Modules Introduction This document provides example steps for configuring the Kepware KEPServerEX OPC Server for communications with Acromag Busworks Modbus RTU and Modbus TCP/IP Distributed I/O Modules. Once the server is configured, data may be read from or written to the I/O module using...
    How to Configure LabVIEW to Communicate with Modbus I/O Modules Via an OPC Server - 8500881
    Configuring LabVIEW 2009 to Communicate with Acromag BusWorks and EtherStax Modbus I/O Modules via an OPC Server Introduction National Instruments™ LabVIEW can be used to monitor and control Acromag BusWorks ® and EtherStax ® Modbus I/O modules via an OPC server. A separate application note, Configuring Kepware KEPServerEX® 5.0 for communications with Acromag BusWorks and EtherStax...
  • Specs & Data Sheets

    Manuals

    942MB User Manual (Log in to download the file)

    How to Use SIIG USB-to-Serial Cable With Windows Tech Note (Log in to download the file)

  • Software

    900C-SIP: Modbus RTU Configuration Software Information Page (Log in to download the file)
  • Accessories

    • Compare

      5034-202: RS-485 to 3-wire Cable Converter and Cable

      RS-485 to 3-wire cable converter and cable, DB-9M to 3 x 12AWG RS-485 cable, 8 ft.
      Select options
    • Compare

      5034-214: RS232 to RS485 Serial Port Converter

      Non-isolated RS232-to-RS485 serial port converter, RS232 port-powered, DB-9F to DB-9F.
      Select options
    • Compare

      900C-SIP: Configuration Software Interface Package

      • Configuration Software
      • USB-to-RS232 Adapter
      • RS232-to-RS485 Adapter
      • Interface Cable
       
      Select options
  • Additional information

    Additional information

    Weight 16 oz
    Dimensions 1.5 × 5.5 × 4.5 in
    Part Number

    942MB-0900: 2 input channels

    Configuration

    Windows Software Configuration

    Communication

    Modbus-RTU, RS422/485

    Product Series

    BusWorks 900MB