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Product short description:
  • 4 input channels, thermocouple (types J, K, T, R, S, E, B, N) or millivolt (±100mV DC) input
  • 4 alarm channels, open drain MOSFETS (1A DC loads, 0 to 35V DC)
  • 10 to 36V DC, 24V AC power
  • Modbus-RTU high-speed RS-485

This signal conditioner is a four-channel analog input module with four discrete outputs. It filters and linearizes thermocouple inputs while providing isolation between input, output, power, and network circuits. Cold junction compensation and upscale/downscale sensor break detection are standard.

 

924MB: Thermocouple/milliVolt Modbus-RTU Input Module with Limit Alarms Description

This signal conditioner is a four-channel analog input module with four discrete outputs. It filters and linearizes thermocouple inputs while providing isolation between input, output, power, and network circuits. Cold junction compensation and upscale/downscale sensor break detection are standard. AC and DC power sources are supported with non-polarized, diode-coupled terminals.

The programmable inputs accommodate eight thermocouple types plus wide-range millivolt signals. Flexible discrete outputs operate as alarms or on/off controllers. As limit alarms, each discrete output can be configured with high and/or low set-points exclusively tied to an analog input channel. Alarm trips function without host communication enabling low-cost stand-alone alarms as well as local backup for the primary control system. Otherwise, on/off control is based on commands issued by the host system.

Combining flexible transmitter functions, mixed signal I/O, alarm support, 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).

Thermocouple or Millivolt Input
Limit Alarms or Discrete Outputs

Model: 924MB: 4 input channels.

Input
Four input channels: Thermocouple (types J, K, T, R, S, E, B, N) ±100mV DC.

Output
Four output channels: Open-drain MOSFETs (1A DC loads) 0 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

General Output

Resolution
±100mV DC input: 0.1%.
Thermocouple input: 0.1°C (0.18°F).

Ambient Temperature Effect: Better than ±0.005% of input span per °C, or ±1.0uV/°C, whichever is greater.

Noise Rejection
Normal mode: 40dB @ 60Hz, typical.
Common mode: 140dB @ 60Hz, typical.

Input Filter Bandwidth: -3dB at 3Hz, typical.

Input Conversion Rate: 90ms per channel.

Thermocouple Input

Thermocouple Input Ranges: Thermocouple type user-configured. Type selected applies to all channels. Signal linearization, cold-junction compensation, and open circuit or lead break detection are included.

TC                  °C Range (°F Range)                        Accuracy
J            -210 to  760°C   (-346 to 1400°F)                ±0.5°C
K            -200 to 1372°C (-328 to 2502°F)                ±0.5°C
T            -260 to  400°C  (-436 to 752°F)                   ±0.5°C
R             -50 to 1768°C (-58 to 3214°F)                    ±1.0°C
S             -50 to 1768°C (-58 to 3214°F)                    ±1.0°C
E           -200 to 1000°C (-328 to 1832°F)                   0.5°C
B            260 to 1820°C (500 to 3308°F)                  ±1.0°C
N          -230 to 1300°C (-382 to 2372°F)                 ±1.0°C
Note 1: Accuracy is given with CJC switched off.
Relative inaccuracy with CJC enabled may increase by ±0.5°C.

Thermocouple Break Detection: TC sensor failure can be configured for either upscale or downscale. Selection applies to all channels.

DC milliVolt Input

milliVolt Input Ranges: ±100mV DC.

milliVolt Input Accuracy: ±0.1% of input range.

Discrete Output

Output Type: Four independent open drain MOSFET switches with a common return that operate as low-side switches.

Output Voltage Range
0 to 35V DC, 1A DC maximum for each output.
External voltage source required.

Output ON Resistance: 0.15 ohms maximum.

Operation: Digital outputs are set to their OFF state following a software or power-on reset. Outputs can optionally be set to user-defined states following a watchdog timeout. Watchdog timeout output control takes precedence over limit alarm control. Alarm control takes precedence over host control.

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

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

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

Power and Isolation

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

Supply Current
Supply           Current Draw
10V DC     100mA maximum
24V DC       45mA maximum
24V AC       85mA rms maximum

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)
  • 16-bit sigma-delta A/D yields 0.1°C resolution and 0.5°C measurement accuracy
  • Thermocouple linearization and sensor break detection ensure reliable measurements
  • Four discrete outputs enable local temperature limit alarms or host-controlled on/off switching
  • Heavy-duty 1A solid-state relays provide dependable on/off control of industrial devices
  • Self-calibration lowers maintenance costs by reducing periodic manual calibration checks
  • Watchdog timers provide a configurable fail-safe output state for use when host I/O communication is lost
  • Four-way isolation eliminates potential ground loops between power, input, output 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).

 

 

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

924MB 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 2 × 4.5 × 5.5 in
Configuration

Windows Software Configuration

Part Number

924MB-0900: 4 input channels

Communication

Modbus-RTU, RS422/485

Product Series

BusWorks 900MB

  • Description

    924MB: Thermocouple/milliVolt Modbus-RTU Input Module with Limit Alarms Description

    This signal conditioner is a four-channel analog input module with four discrete outputs. It filters and linearizes thermocouple inputs while providing isolation between input, output, power, and network circuits. Cold junction compensation and upscale/downscale sensor break detection are standard. AC and DC power sources are supported with non-polarized, diode-coupled terminals.

    The programmable inputs accommodate eight thermocouple types plus wide-range millivolt signals. Flexible discrete outputs operate as alarms or on/off controllers. As limit alarms, each discrete output can be configured with high and/or low set-points exclusively tied to an analog input channel. Alarm trips function without host communication enabling low-cost stand-alone alarms as well as local backup for the primary control system. Otherwise, on/off control is based on commands issued by the host system.

    Combining flexible transmitter functions, mixed signal I/O, alarm support, 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).

    Thermocouple or Millivolt Input
    Limit Alarms or Discrete Outputs

    Model: 924MB: 4 input channels.

    Input
    Four input channels: Thermocouple (types J, K, T, R, S, E, B, N) ±100mV DC.

    Output
    Four output channels: Open-drain MOSFETs (1A DC loads) 0 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

    General Output

    Resolution
    ±100mV DC input: 0.1%.
    Thermocouple input: 0.1°C (0.18°F).

    Ambient Temperature Effect: Better than ±0.005% of input span per °C, or ±1.0uV/°C, whichever is greater.

    Noise Rejection
    Normal mode: 40dB @ 60Hz, typical.
    Common mode: 140dB @ 60Hz, typical.

    Input Filter Bandwidth: -3dB at 3Hz, typical.

    Input Conversion Rate: 90ms per channel.

    Thermocouple Input

    Thermocouple Input Ranges: Thermocouple type user-configured. Type selected applies to all channels. Signal linearization, cold-junction compensation, and open circuit or lead break detection are included.

    TC                  °C Range (°F Range)                        Accuracy
    J            -210 to  760°C   (-346 to 1400°F)                ±0.5°C
    K            -200 to 1372°C (-328 to 2502°F)                ±0.5°C
    T            -260 to  400°C  (-436 to 752°F)                   ±0.5°C
    R             -50 to 1768°C (-58 to 3214°F)                    ±1.0°C
    S             -50 to 1768°C (-58 to 3214°F)                    ±1.0°C
    E           -200 to 1000°C (-328 to 1832°F)                   0.5°C
    B            260 to 1820°C (500 to 3308°F)                  ±1.0°C
    N          -230 to 1300°C (-382 to 2372°F)                 ±1.0°C
    Note 1: Accuracy is given with CJC switched off.
    Relative inaccuracy with CJC enabled may increase by ±0.5°C.

    Thermocouple Break Detection: TC sensor failure can be configured for either upscale or downscale. Selection applies to all channels.

    DC milliVolt Input

    milliVolt Input Ranges: ±100mV DC.

    milliVolt Input Accuracy: ±0.1% of input range.

    Discrete Output

    Output Type: Four independent open drain MOSFET switches with a common return that operate as low-side switches.

    Output Voltage Range
    0 to 35V DC, 1A DC maximum for each output.
    External voltage source required.

    Output ON Resistance: 0.15 ohms maximum.

    Operation: Digital outputs are set to their OFF state following a software or power-on reset. Outputs can optionally be set to user-defined states following a watchdog timeout. Watchdog timeout output control takes precedence over limit alarm control. Alarm control takes precedence over host control.

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

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

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

    Power and Isolation

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

    Supply Current
    Supply           Current Draw
    10V DC     100mA maximum
    24V DC       45mA maximum
    24V AC       85mA rms maximum

    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)
    • 16-bit sigma-delta A/D yields 0.1°C resolution and 0.5°C measurement accuracy
    • Thermocouple linearization and sensor break detection ensure reliable measurements
    • Four discrete outputs enable local temperature limit alarms or host-controlled on/off switching
    • Heavy-duty 1A solid-state relays provide dependable on/off control of industrial devices
    • Self-calibration lowers maintenance costs by reducing periodic manual calibration checks
    • Watchdog timers provide a configurable fail-safe output state for use when host I/O communication is lost
    • Four-way isolation eliminates potential ground loops between power, input, output 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).

     

     

  • 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

    924MB 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 2 × 4.5 × 5.5 in
    Configuration

    Windows Software Configuration

    Part Number

    924MB-0900: 4 input channels

    Communication

    Modbus-RTU, RS422/485

    Product Series

    BusWorks 900MB