What is a Fieldbus Terminator and How Does it Work?
A fieldbus terminator is a necessary component in fieldbus communication systems, acting as a 1 µF capacitor and a 100 Ω resistor in series. Its major function is to ensure signal integrity by routing fieldbus current and reducing electrical reflections. These reflections, induced by cabling irregularities, can produce noise, jitter, and incorrect data. Terminators improve the stability of the transmission signal by eliminating distortions.
Each fieldbus segment requires two terminators, one at the beginning and one at its end. The terminator at the beginning is frequently built into components such as power supply modules, conditioners, or motherboards, protecting space and simplifying system design. The terminator at the end is usually installed as an independent equipment or integrated into a junction box. Proper placement of these terminators is crucial; missing or extra terminators can harm the network.
Too many terminators in a segment weaken the signal—one extra terminator can reduce the signal intensity by approximately 30%. Missing terminators, on the other hand, significantly amplify the signal, increasing it by around 70% for each absent unit. This imbalance could limit communication and cause network instability.
Fieldbus terminators not only maintain signal strength but also help to eliminate electrical reflections. These reflections are identical to waves bouncing off barriers and can distort the signal. Terminators provide that communication flows smoothly across the network by reducing reflections.
Fieldbus terminators, despite their modest size, are critical to ensuring system reliability. To avoid signal deterioration or amplification concerns, one should be placed at the beginning and conclusion of the section, respectively.