---
pdfexport: true
alias: tutorials-sched-maintenance
tags:
- scheduling
description: "Scheduling incorporates maintenance activities as unavailability periods impacting resource and durable availability"
---

# Scheduling Maintenance

Maintenance represents an important constraint in scheduling in two ways:

* Corrective maintenance: whenever there is a Resource or Durable breakdown, an Ad-Hoc Maintenance Activity Order (MAO) should be issued for that equipment. Scheduling will consider the MAO as an unavailability period for the Resource or Durable.
* Preventive maintenance: the preventive maintenance plans for a certain Resource or Durable can schedule MAOs with a frequency specified by the user. These MAOs in turn will be considered by scheduling, thereby limiting the availability of the Resource/Durable

Scheduling considers MAOs which are associated with Resources or Durables of the scheduling universe, that have not been marked with Ignore in Scheduling and that have one of two Schedule Types:

* Ad-hoc
* Time based

!!! info
	Note that for Preventive Time Based Activities, since Scheduling will only consider MAOs which exist at any given point, it is advised to set the Maintenance Activity in the Maintenance Plan with the Schedule Next Mode = True configuration, so as to enable the Number of Instances to Schedule property, which allows the user to set enough MAOs to cover scheduling's planning horizon. Otherwise, only the next instance of the Maintenance Activity will be created, therefore not having the real impact of the Maintenance Plan in the Resource's/Durable's availability.

The next picture shows a schedule scenario where two ad-hoc maintenance activity orders are requested for the resources Laser Trimming - 01 and Laser Trimming - 03, and where a daily preventive maintenance plan is applied for the contact printing resources.

![Screenshot showing a maintenance schedule with MAOs (Maintenance Activities) listed.](../../../../images/schedulingMAO.png)

!!! info
	Although both Resource and Material MAOs are taken into consideration, only the Resource MAOs are shown in the GUI.

## Schedule Scenario Maintenance Activity

To support the scheduling of various types of calibration activities that are often required on the shop floor, a Schedule Scenario supports a type of Maintenance Activity that corresponds to these calibration activities which is predicted to take place at any given moment. Although this activity does not hold the properties of a traditional Schedule Scenario Job, you can see this type of activity in the Schedule View, represented by a dark grey background and a dashed black border:

![Screenshot showing a maintenance activity scheduling scenario on September 2, 2022.](../../../../images/scheduleScenarioMaintenanceActivity.png)

After the Schedule Scenario Maintenance Activity is created, a synchronization of the Schedule Scenario is triggered.

!!! warning
	This type of entity is only available through API access and cannot be created directly in the MES.