These modules were specially designed to provide appropriate impedance for fieldbus networks.

• DF53 (4 ports)
• DF53-FC (4 ports)
• DF98 (2 ports)

The purpose of this impedance is to implement an output circuit where the impedance is greater than 3 KΩ, and when assembling in parallel with two 100 Ω ±2% terminators, it results in 50 Ω line impedance approximately. This impedance can be implemented in a passive mode (50 Ω resistance in series with a 100 mH inductance) or in an active mode, through an impedance control circuit.

The fieldbus power supply impedance is a non-isolated, active impedance control device, in compliance with IEC 61158-2 standard. This device provides output impedance which, in parallel with the two bus terminators (a 100 Ω resistor in series with a 1 mF capacitor) required by the standard, results in a pure resistive line impedance for a broad frequency range. DF53 and DF98 were designed to work in non-hazardous areas.