Overview

Analog Input Modules such as the 3700A, 3703E, 3704E, 3720, and 3721 have three independent input channels. Each channel processes variable voltage signals from each point, converts them to digital values, and transmits these values to the three Main Processors upon request. To ensure accurate data for each scan, a mid-value selection algorithm is used to select one value. The design ensures that a single failure on one channel does not affect the others.

Specifications

• Color Code: Yellow

• Number of Input Signals: 64, single-ended

• Input Update Rate: 10 ms

• Resolution: 12 bits or 14 bits programmable

• Accuracy: < 0.15% of FSR from 0° to 60° C

• Input Resistance (Load): 10 MΩ (DC), minimum

• Input Resistance at Power Off: 140 kΩ (DC), typical

• Channel-to-Channel Isolation: 420 kΩ, typical

• Normal Mode Rejection:

  • -3 dB @ 8 Hz
  • -17 dB @ 60 Hz
  • -23 dB @ 120 Hz

• Input Voltage Range: 0 to 5 VDC

• Input Over-Range Measurement: +6%, 0 to 5.3 V, 0 to 10.6V

• Logic Power: < 12 watts

• Input Over-Range Protection: 150 VDC continuous, 115 VAC continuous

• Input Current Range: 0 to 20 mA (plus 6% over-range) with 250 Ω shunt resistor

• Field to System Isolation: 800 VDC minimum

• Module Status Indicators: Pass, Fault, Active, Field

• Input Diagnostic Fault Coverage:

  • Minimum Input Change: 0.5% of full scale
  • Input Change Sample Period: 10 ms
  • Minimum Period of Mis-Compares: 25 samples