You modify properties and attributes when you set them or when you call a configuration VI or function that sets them.
Set the properties or attributes or call any configuration VIs or functions before reading back any property or attribute values for the following reasons:
The driver coerces the read values depending on the current session configuration. If you read a property or attribute value and then set other properties or attributes, the value read may no longer be valid.
The driver verifies that the device configuration is valid when the property or attribute is read. You may receive an error when reading a property or attribute if the configuration is not valid at that point, even when a setting later could make it valid.
The driver verifies the current configuration when it reads a property or attribute. If you change any of the settings later, the driver must re-validate those settings.