Relationships
Relationships describe the connections between your assets.
Each relationship has a start point, an end point and a direction. For example, a light switch feeds power to a light-bulb in the ceiling, so in this case the 'Power' relationship between the two moves from the switch to the bulb.
ARDI uses relationships to provide detail about how your various assets are physically and logically connected.
Relationship Types
Relationships fit into three major types…
You can click on the names above for detail, but as a basic summary…
Physical Relationships define actual, physical connections between assets, such as power cables, network connections, piping or WiFi network links.
Logical Relationships describe non-physical associations, such as describing concepts such as…
- Is A Tool For
- Controls
- Is Next in Sequence
- Is Dependent On
These sorts of relationships are usually not obvious when you are out in the field, since there isn't the same physical connection as found in physical relationships.
Hierarchical Relationships describe how assets are associated based on some form of logical hierarchy
Hierarchies
A special note about hierarchies - an asset may only ever be attached (related) to a hierarchy at one point. An asset can't be in two locations, two places in the org chart etc.
If you have a situation where you would like to place an asset in more than one hierarchy, consider using types instead, as these can fulfill a similar goal.
Directional Names
Relationships have directional names. As well as the main name that describes the relationship as a whole (ie. Water Supply or Mains Power), they also have a description that applies when the relationship is going upstream (from child to parent) and another description that applies when it is going downstream (from parent to child).
For example, the relationship 'Mains Power' is a physical relationship describing the power coming from the power grid.
It has a relationship name of 'Mains Power', but it's upstream name is 'Powered By' and it's downstream name is 'Powers'.
These directional names are used when trying to describe these relationships in plain language. Rather than saying 'The light bulb has a downstream Mains Power relationship with the switch', we instead say 'The light bulb is powered by the switch'. And vice-versa, 'The switch powers the light bulb'.
Avoiding Cycles
While ARDI can deal with cyclic relationships - a relationship that flows back up to its source - we generally suggest avoiding their use.
This is largely because ARDI is designed to have a clear concept of 'upstream' and 'downstream' relationships, and making a cycling relationship makes those terms difficult.
However, cyclic relationships to exist in real-world processes. Closed-loop systems and such as cooling and hydraulic systems and systems that maximise efficiency by re-circulating their water are common.
To get around this - while at the same time making the relationships between your assets even more informative - we suggest splitting loops such as this into two relationships.
In a hydraulic closed systems, you can have a 'Hydraulic Supply' and 'Hydraulic Return' relationship, which then clearly marks if the oil within the hydraulic line is travelling to where it is used, or from where it has been used.
Similar Relationships
In some applications your media remains the same as it passes through your process - for example, the water being pumped through your cooling system may change temperature, but it's always water.
However, in other applications, it's the processes job to change the media into different forms.
A good example of this is in mining, where rock crushers usually send the crushed material to a screen, which separates it into small pieces and large pieces. The small pieces fall through the screen and continue the process while the large pieces are diverted back around to be crushed again.
At each stage, the media has a different name. For example, 'Coarse Ore' is fed into the crusher, but 'Granulated Ore' comes out through the screen on the other side.
Administering Relationships
See the article Managing Relationships to see an example of how new relationships are created, existing relationships are edited, and useless ones removed.