According to the BACnet protocol documentation:

Monitors one or more properties of one or more referenced objects, either in the same device as the Trend Log Multiple object or in an external device. When predefined conditions are met, the object saves ("logs") the value of the properties and a timestamp into an internal log buffer for subsequent retrieval. The data may be logged periodically or when "triggered" by a write to the Trigger property. Errors that prevent the acquisition of the data, as well as changes in the status or operation of the logging process itself, are also recorded. Each timestamped log buffer entry is called a "log record".

Objects of type trendLogMultiple have the following properties:

•ackedTransitions

•alignIntervals

•bufferSize

•description

•enable

•eventAlgorithmInhibit

•eventAlgorithmInhibitRef

•eventDetectionEnable

•eventEnable

•eventMessageTexts

•eventMessageTextsConfig

•eventState

•eventTimeStamps

•intervalOffset

•lastNotifyRecord

•logBuffer

•logDeviceObjectProperty

•logInterval

•loggingType

•notificationClass

•notificationThreshold

•notifyType

•objectIdentifier

•objectName

•objectType

•profileLocation

•profileName

•propertyList

•recordCount

•recordsSinceNotification

•reliability

•reliabilityEvaluationInhibit

•startTime

•statusFlags

•stopTime

•stopWhenFull

•tags

•totalRecordCount

•trigger