When testing computer-controlled systems, the digital multimeter should have an input impedance of at least what value?

In testing computer-controlled systems, it is critical for the digital multimeter to have a high input impedance, ideally at least 10 megohms. This high input impedance is essential because it ensures minimal loading effects on the circuit being tested. When a multimeter has low input impedance, it can draw significant current from the circuit, which may alter the circuit's operation or produce inaccurate readings.

A multimeter with 10 megohms of input impedance will provide a more accurate representation of the voltage or signal present in the system without influencing its behavior. This characteristic is particularly important in sensitive electronic circuits, such as those in computer-controlled systems, where precision is crucial for diagnosing issues and ensuring proper functioning.

While lower input impedance values might still function for basic measurements, they are not suitable for more advanced applications where the integrity of the circuit's response must be maintained. Thus, a multimeter with an input impedance of 10 megohms is the best choice for effectively testing computer-controlled systems.