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Product short description:
  • Active-Low Inputs, Sinking Outputs (Low-Side Switching)
  • 12 input and/or 12 output channels
  • 0 to 35V DC I/O range
  • 10 to 36V DC, 24V AC power
  • Modbus-RTU high-speed RS-485

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.

 

 

901MB, 902MB, 903MB: Multi-Channel Modbus-RTU Discrete I/O Modules Description

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, non-polarized, diode-coupled terminals.

The open-drain outputs are intended for current-sinking or low-side switching applications. The buffered inputs are active-low. These models are the complement of the 904, 905, and 906 units which have open-source, high-side output switches and active-high inputs. Socketed pull-up resistors are easily removed or exchanged to satisfy your application requirements.

The 903MB model has twelve input/output points that may be used as inputs or outputs on a bit-by-bit basis. Outputs may be read back to verify output settings.

Combining flexible I/O types, wide I/O ranges, 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).

Active-Low Inputs Sinking Outputs (Low-Side Switching)

Models
901MB: 12 input channels.
902MB: 12 output channels.
903MB: 12 input/output channels.

Input
Twelve input channels (901, 903 models only).
0 to 35V DC.

Output
Twelve output channels (902, 903 models only).
O to 35V 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

Discrete Inputs (901 & 903 models only)

Input Type: 12 active-low, buffered inputs, with a common connection. Inputs include transient suppression devices and series connected 100K ohm resistors, plus diode over-voltage clamps to the internal +5V supply.

Input Signal Voltage Range: 0 to 35V DC, maximum.

Input Current: 293μA, typical at 35V DC.

Input Signal Threshold
TTL compatible with 100mV of hysteresis, typical.
Low-to-High threshold is 1.7V DC.
High-to-Low is 1.6VDC, typical.
Limited to TTL levels of 0.8VDC (max. LOW level) and 2.0VDC (min. HIGH level).

Input Resistance: 100K ohms, typical.

Input Hysteresis: 100mV DC, typical.

Discrete Outputs (902 & 903 models only)

Output Type: 12 independent, open-drain, DMOS MOSFET switches with a common source connection that operate as low-side switches.

Output Voltage Range
0 to 35V DC max. (0 to 500mA/channel continuous).
External voltage source required.

Output ON Resistance: 0.28 ohms maximum.

Output Response Time
Force Single Coil: Output updates within 250μs of receipt of a command.
Force Multiple Coils: First coil updates in 250μs, followed successively by additional coils every 180μs.

General

I/O Pull-ups and Socket: 5.6K ohm pull-up resistor SIPs are installed in sockets at each port (four-channels per port).

Excitation (per port): External excitation voltage for each four-channel port is limited to 35V or less.

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

  • Read Coil (Output) Status
  • Read Input Status
  • Read Holding Registers
  • Force Single Coil (Output)
  • Preset Single Register
  • Reset Slave
  • Force Multiple Coils (Outputs)
  • Preset Multiple Registers
  • Report Slave ID

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

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

Supply Current
Supply         Current Draw
10V DC    130mA maximum
24V DC      54mA maximum
24V AC      95mA maximum

Isolation
1500V AC for 60 seconds or 250V AC continuous.
3-way isolation between I/O, network, and power circuits.

  • 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 loop-back 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 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 micro controller 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

901MB, 902MB, 903MB 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 10 oz
Dimensions 4.5 × 1.5 × 5 in
Part Number

901MB-0900: 12 input channels, 902MB-0900: 12 output channels, 903MB-0900: 12 input & 12 output channels

Configuration

Windows Software Configuration

Communication

Modbus-RTU, RS422/485

Product Series

BusWorks 900MB

  • Description

    901MB, 902MB, 903MB: Multi-Channel Modbus-RTU Discrete I/O Modules Description

    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, non-polarized, diode-coupled terminals.

    The open-drain outputs are intended for current-sinking or low-side switching applications. The buffered inputs are active-low. These models are the complement of the 904, 905, and 906 units which have open-source, high-side output switches and active-high inputs. Socketed pull-up resistors are easily removed or exchanged to satisfy your application requirements.

    The 903MB model has twelve input/output points that may be used as inputs or outputs on a bit-by-bit basis. Outputs may be read back to verify output settings.

    Combining flexible I/O types, wide I/O ranges, 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).

    Active-Low Inputs Sinking Outputs (Low-Side Switching)

    Models
    901MB: 12 input channels.
    902MB: 12 output channels.
    903MB: 12 input/output channels.

    Input
    Twelve input channels (901, 903 models only).
    0 to 35V DC.

    Output
    Twelve output channels (902, 903 models only).
    O to 35V 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

    Discrete Inputs (901 & 903 models only)

    Input Type: 12 active-low, buffered inputs, with a common connection. Inputs include transient suppression devices and series connected 100K ohm resistors, plus diode over-voltage clamps to the internal +5V supply.

    Input Signal Voltage Range: 0 to 35V DC, maximum.

    Input Current: 293μA, typical at 35V DC.

    Input Signal Threshold
    TTL compatible with 100mV of hysteresis, typical.
    Low-to-High threshold is 1.7V DC.
    High-to-Low is 1.6VDC, typical.
    Limited to TTL levels of 0.8VDC (max. LOW level) and 2.0VDC (min. HIGH level).

    Input Resistance: 100K ohms, typical.

    Input Hysteresis: 100mV DC, typical.

    Discrete Outputs (902 & 903 models only)

    Output Type: 12 independent, open-drain, DMOS MOSFET switches with a common source connection that operate as low-side switches.

    Output Voltage Range
    0 to 35V DC max. (0 to 500mA/channel continuous).
    External voltage source required.

    Output ON Resistance: 0.28 ohms maximum.

    Output Response Time
    Force Single Coil: Output updates within 250μs of receipt of a command.
    Force Multiple Coils: First coil updates in 250μs, followed successively by additional coils every 180μs.

    General

    I/O Pull-ups and Socket: 5.6K ohm pull-up resistor SIPs are installed in sockets at each port (four-channels per port).

    Excitation (per port): External excitation voltage for each four-channel port is limited to 35V or less.

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

    • Read Coil (Output) Status
    • Read Input Status
    • Read Holding Registers
    • Force Single Coil (Output)
    • Preset Single Register
    • Reset Slave
    • Force Multiple Coils (Outputs)
    • Preset Multiple Registers
    • Report Slave ID

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

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

    Supply Current
    Supply         Current Draw
    10V DC    130mA maximum
    24V DC      54mA maximum
    24V AC      95mA maximum

    Isolation
    1500V AC for 60 seconds or 250V AC continuous.
    3-way isolation between I/O, network, and power circuits.

  • Features & Benefits

    • 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 loop-back 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 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 micro controller 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

    901MB, 902MB, 903MB 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 10 oz
    Dimensions 4.5 × 1.5 × 5 in
    Part Number

    901MB-0900: 12 input channels, 902MB-0900: 12 output channels, 903MB-0900: 12 input & 12 output channels

    Configuration

    Windows Software Configuration

    Communication

    Modbus-RTU, RS422/485

    Product Series

    BusWorks 900MB