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Combination Module: 2 Ch. MIL-STD-1553 & 12 Ch. Discrete I/O

The CM8 module is a combination of NAI's MIL-STD-1553B module, FTB, and Enhanced Discrete I/O module, DT4. The CM8 offers twelve channels of discrete I/O and two channels of MIL-STD-1553B communications. The twelve discrete I/O channels are programmable as either input (voltage or contact sensing with programmable, on-module pull-up/pull down current sources), or output (current source, sink, or push-pull) up to 500 mA per channel from an applied, external 3-60 VCC source. The discrete I/O channels also provide additional functionality modes such as Pulse Width Modulation (PWM) output mode and Pattern Generator output mode. The two MIL-STD-1553B communications channels feature a dual, redundant, balanced-line, physical layer; a (differential) network interface; time division multiplexing; half-duplex command/response protocol; and up to 31 remote terminals (devices).

Looking for the CM1? The CM8 function module offers the improved assisted mode MIL-STD-1553B communications. View more information this Assisted Mode Product Improvement. Please visit the CM1 archive page for CM1 details.

  • 12 channels available as inputs or outputs
  • Programmable for Input (voltage or contact sensing) or Output (current source, sink or push-pull) per channel/bank
  • Ability to current share, by connecting multiple outputs in parallel, to sink/source up to 2 A per bank
  • Ability to handle high inrush current loads (for example, two #327 incandescent lamps in parallel)
  • Supports "dual turn-on" (series channel output) applications (for example, dual series "key" missile launch control)
  • Pulse Width Modulation (PWM) output mode
  • Pattern Generator output mode
  • Timing measurement of inputs with 10 μs resolution
  • Programmable debounce circuitry with selectable time delay eliminates false signals resulting from relay contact bounce
  • Built-In-Test runs in background constantly monitoring system health for each channel
  • Ability to sense broken input connection and if input is shorted to +V or to ground
  • Ability to read I/O voltage and output current for improved diagnostics (indicates if load is connected)
  • Additional Enhanced Input Mode Operation: Pulse Measurements, Transition Timestamps, Transition Counters, Period Measurement and Frequency Measurement
  • Additional Enhanced Output Mode Operation: PWM Output and Pattern Generator Output
  • Independent (dual-redundant) MIL-STD-1553 interface channels: Bus Controller (BC), Remote Terminal (RT), and Bus Monitor (BM) operation
  • Support for RT and BM combination
  • 64 words on-board memory/channel
  • IP-core register-compatible with DDC™ family of devices
  • Automatic message return supported
  • Automatic message retry
  • Multiple message processing
  • Hardware acceleration for rapid setup/message Tx/Rx

  • MIL-STD-1553B Characteristics: see below
  • Number of Channels: 2 Dual-Redundant(Transformer-Coupled)
  • IP Core: DDC® core register compatible/hardware acceleration for rapid setup, transmission and/or reception of packets.
  • Onboard RAM: 128k words onboard memory per channel.
  • Operational Modes: Programmable as Bus Controller (BC), Remote Terminal (RT), Bus Monitor (BM), or BM/RT.
  • Output Signal: 28 Vp-p, as per MIL-STD-1553
  • Discrete I/O Input Characteristics: see below
  • Input Range: 0 to 60 VDC. Programmable for either voltage or switch closure sensing.
  • Overvoltage Surge Protection: 80 VDC max. (< 50 ms); 100 VDC max. (< 1 µs)
  • Voltage/Content Sensing: Software selectable per bank. When the input channel is utilized for direct voltage sense, VCC is not required. When input is used to detect switch closures, VCC is required to provide a current source (pull-up). VCC per channel bank must be between 5 VDC min. and 60 VDC max. A module has 4 VCC banks, each with 6 channels for a total of 24 channels/modules.
  • Input Pulse Detection: A pulse, of 20.48 µs minimum width, will be sensed and reported by the appropriate High-Low or Low-High transition status/interrupt.
  • Input Impedance: 1 MΩ (with or without power applied to module).
  • Switching Threshold: Four levels (High, Low, Short to +V, Short to ground) are programmable from 0 to 60 VDC with 10-bit resolution.
  • Voltage Measurement: User can read input voltage of each channel. LSB= 100 mV; Accuracy: ±3 LSB's (300 mV) over temp.
  • HIGH/LOW Differential (Hysteresis): 0.25 V min. recommended. Programmable by using Upper & Lower thresholds.
  • Debounce: Programmable per channel from 0 to 366 ms (LSB= 10 µs; 16-bit resolution).
  • Update Rate: Each channel is updated every 20.48 µs.
  • Discrete I/O Output Characteristics: see below
  • Output Formats: Low-Side (I sink), High-Side (I source) or Push-Pull (I source-sink); programmable per channel.
  • Output Voltage Range: 0 to 60 VDC. (Output voltage is defined by the user provided VCC applied to channel bank) Low-side drive does not require VCC. High-side and push-pull drive requires VCC.
  • Overvoltage Surge Protection: 80 VDC max. (< 50 ms); 100 VDC max. (< 1 μs)
  • Output Current: 0.5 A maximum (28 V VCC typical) per channel. 2 A total per VCC bank (total Module capacity 8 A). Measurement accuracy: ±10% ±25 mA.
  • Output Impedance: < 1 Ω (0.5 Ω typical)
  • Current Share Applications: 0.5 A maximum (28 V VCC typical) per channel. 2 A total per VCC bank (total Module capacity 8 A). Each channel can be programmed to generate frequency, pulse or arbitrary pulse width with 20 microsecond resolution. Short circuit protected.
  • Overcurrent Protection: Low current (average): > 650 mA average over 3 ms. High current (pulse): > 6 amps for less than or equal to 30 µs.
  • General Characteristics: see below
  • Power: 5 VDC @ 1100 mA, MIL-STD-1553, estimated at 100% duty cycle (1 channel), Discrete I/O, typical, excluding external VCC related current
  • Weight: 1.75 oz. (50 g)
Block Diagram
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