Which type of I/O module would be used to read voltage values?

The selection of an analog input module is appropriate for reading voltage values because these modules are specifically designed to interpret continuous, varying signals, such as voltage or current. Analog signals can represent a range of values, such as temperature, pressure, or in this case, voltage.

Analog input modules convert these continuous signals into a digital format that the ControlLogix system can process. This conversion allows for precise readings and the ability to monitor changes in voltage levels over time. In industrial applications, this capability is essential for capturing real-time data from sensors that generate analog outputs.

On the other hand, digital input modules handle discrete signals, which represent states (on/off) rather than a range; hence they wouldn’t be able to measure voltage levels. Similarly, bit output and relay output modules are used for controlling devices, not for measuring input values. They are designed to switch states or power devices, which does not involve reading variable voltage signals. Thus, the use of an analog input module is necessary and appropriate for applications that require capturing voltage values.