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An Triconex 3721 analog input (AI) module comprises three independent input channels. Each input channel receives variable voltage signals from each point, converts them to digital values, and transmits the values to the three main processor modules on demand. In TMR mode, a mid-value selection algorithm selects one value to ensure correct data for every scan.
Sensing of each input point prevents a single failure on one channel from affecting another channel. Each analog input module continuously conducts diagnostics for each channel. The activation of the Fault indicator for a module, in response to any diagnostic failure on any channel, subsequently activates the chassis alarm signal. It’s essential to note that the module’s Fault indicator only reports a channel fault, not a module failure, as the module can operate properly with up to two faulty channels.
Analog input modules support hot-spare capability, allowing online replacement of a faulty module.
Triconex 3721 Product Specifications:
- Voltage: 0 to 5VDC or -5 to +5VDC (selectable using TriStation software)
- Type: TMR (Triple Modular Redundant)
- No. of Input Points: 32 differential, DC-coupled
- Isolated Points: Yes
- Input Update Rate: 10 ms
- Resolution: 12 bits or 14 bits (programmable)
- Accuracy: < 0.15% of FSR from 0°C to 60°C
- Input Resistance (load): ≥ 10 MΩ (DC), minimum
- Power-Off Resistance: ≥ 140 kΩ (DC), typical
- Common Mode Rejection: -85 dB (DC to 100 Hz)
- Common Mode Range: -12V to +12V peak
- Leg-to-Leg Isolation: 420 kΩ, typical
- Normal Mode Rejection: -3 dB @ 8Hz, -17 dB @ 60Hz, -23 dB @ 120Hz
- Input Overrange Protection: 150 VDC/115 VAC continuous
- Current Range: 0-20 mA with 250 Ω shunt resistor
- Diagnostic Indicators: Module Status – PASS, FAULT, ACTIVE, FIELD
- Color Code: Yellow
For more detailed parameters of Triconex 3721 Analog input module, please read the PDF: 3640E
