A bipolar input module can accept signals that:

• A. Swing between negative and positive value
• B. Are always positive
• C. Are digital only
• D. Are zero or full-scale

Answer: (A)

Bipolar input modules measure signed signals, allowing negative and positive values around a zero reference. This means the input can represent a value from a negative range up to a positive range, which is essential for sensors whose outputs cross zero or have opposite polarities. If a module were unipolar, it would only accept nonnegative values and would lose information from negative excursions. Digital-only inputs read on/off signals, not analog magnitudes, so they don’t capture positive and negative analog values. Describing the range as zero or full-scale implies only a single-sided span, missing the negative half of the signal. So the best match is signals that swing between negative and positive values.