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 1.7VDC 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

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

    • 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
    $300$325
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    904MB, 905MB, 906MB: Multi-Channel Modbus-RTU Discrete I/O Modules

    • Active-High Inputs, Sourcing Outputs (High-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
    $300$325
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    913MB, 914MB: DC Current/Voltage Modbus-RTU Input Module with Limit Alarms

    • 4 input channels
    • 0 to 20mA DC (0 to 20A AC with AC sensor) or ±10V DC input range
    • 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
    $385
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    917MB, 918MB: DC Current/Voltage Modbus-RTU Output Modules with Discrete Outputs

    • 4 analog output channels
    • 0 to 20mA or 0 to 10V DC output range
    • 4 discrete output channels, open drain MOSFETS (1A DC loads, 0 to 35V DC)
    • 10 to 36V DC, 24V AC power
    • Modbus RTU high-speed RS-485
     
    $385
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    924MB: Thermocouple/Millivolt Modbus-RTU Input Module with Limit Alarms

    • 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
    $435
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    932MB, 934MB: RTD/Resistance Modbus-RTU Input Modules with Limit Alarms or Discrete Outputs

    • 2 or 4 input channels, RTD (100 ohm Pt, 120 ohm Ni, 10 ohm Cu) or resistance (0 to 500 ohms) input
    • Solid-state relays discrete output, Form A, SPST-NO
    • 10 to 36V DC, 24V AC power
    • Modbus-RTU high-speed RS-485
    $320$435
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    942MB: Frequency/Pulse Counter Modbus-RTU Input Modules with Periodic or Pulse Waveform Input

    • 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
    $385
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    994EN: Ethernet Analog Input Module

    • 16-channel single-ended analog voltage input
    • Modbus TCP/IP communication
    $580$835
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