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2-Wire Transmitter Interface Modules with Loop Power, Bandwidth 100 Hz

The SCM7B35 current input modules accept input signals in the 4-20 mA range from the field and provide a high-level voltage output to the process control system. Current to voltage conversion occurs internal to the module, which is factory calibrated to ensure the highest accuracy.

Loop power is provided by the module, enabling a 2-wire transmitter to be directly connected without the need for a separate dc power supply for the 2-wire transmitter.

These modules incorporate a five-pole filtering approach to maximize both time and frequency response by taking advantage of both Thomson (Bessel) and Butterworth characteristics. One pole of the filter is on the field side of the isolation barrier; four are on the process control system side.

After the initial field-side filtering, the input signal is chopped by a proprietary chopper circuit and transferred across the transformer isolation barrier, sup-pressing transmission of common mode spikes and surges. The signal is then reconstructed and filtered for process control system output.

Modules accept a wide 18 - 35 VDC power supply range (+ 24 VDC nominal). Their compact packages (2.13" x1.705" x0.605" max) save space and are ideal for high channel density applications. They are designed for easy DIN rail mounting using any of the “-DIN” backpanels.

Circuit diagram Dataforth SCM7B35

Block Diagram SCM7B35

PDF Downloads:

2 Modules for Type SCM7B35:

SCM7B35-01 4 to 20 mA SCM7B35 Isolated 2-Wire Transmitter Interface Module With Loop Power and Voltage-Output
SCM7B35-02 4 to 20 mA SCM7B35 Isolated 2-Wire Transmitter Interface Module With Loop Power and Voltage-Output


  • Input: mA-Signal
  • Output: 1 V … 5 V / 0 V … 5 V / 0 V… 10 V / 2 V … 10 V
  • Bandwidth 100 Hz
  • Isolation 1500 Vrms
  • Input protection 120 Vrms
  • Accuracy ± 0.03% (typ.), ± 0.1% (max.)
  • Linearität ± 0.01% (typ.), ± 0.02% (max.)
  • ANSI/IEEE C37.90.1 Input protection
  • CMR 105dB
  • True 2-way isolation
  • NMR: 80dB / Decade > 100 Hz
  • Power Supply 18 to 30 VDC
  • Operating Temperature Range -40°C … +85°C
  • Mix and Match Types on Backpanels possible
  • Dimensions 54.1 x 43.3 x 15.4 mm
  • Optional DIN Rail Mounting
  • CSA certified, CE and ATEX compliant
  • Wide range of accessories
  • Special Solutions on request