Relational Columns - "P1:Tagname"

Cable Scheduler can resolve relationships to lookup data from other records. Relationships are stored in Cable Scheduler by storing the table and IDX value of the related record. Each type of relationship is assigned a letter and number code. For a relationship assigned the letter code 'P' and the number '1', the table and IDX are stored in the columns P1_Table and P1_IDX. This relationship can be used by specifying "P1:" before a column name from the related record.

For example: For the relational column "P1:Tagname", Cable Scheduler will reference the record from the table specified in P1_Table, that has the IDX value specified in P1_IDX. From that record it will fetch the data from the "Tagname" column.

Multiple relationships can be chained together, e.g. "C1:P1:Tagname". Read these from right-to-left as follows: fetch the tagname (Tagname) of the parent (P1) of the component (which would be a terminal) connected via C1 to the component record that is your point of reference (which would be a wire or a cable-core/conductor).

The column specified can itself be a relational column alias. For example, if AREA is an alias of the relational column P1:Tagname, then the relational column C1:<AREA> is equivalent to C1:P1:Tagname.

Relationship Codes used by Cable Scheduler

Some of the letter and number codes for relationships are known and maintained by Cable Scheduler. Any letter or number code that is unknown to Cable Scheduler can still be used to fetch relational data.

Delimiter special meaning for " : " and " | "

The meaning and function of the delimiters in relationships are important. You need to understand how these operate before using them. The colon and the vertical bar have opposite meanings when used in the formulae.

The colon tells the program that you wish to use data from a second record that is pointed to by the relational column in the first and primary record. For example "P1:" for a device (where the device is the primary record of reference) will refer to the enclosure containing the device and the device's tag record will have a P1_IDX column that points to the enclosures record.

The vertical bar tells the program that you wish to use data from a second record that POINTS to the first and primary record with its P1_IDX column. For example "P1|" for a device (where the device is the primary record or reference) will refer to the first terminal of the device. The first terminal's tag record will have a P1_IDX column that points to the device's record.

The colons and bars work equally well in relationships other than parent-child.

Reverse relationships

There are multiple forms of reverse relationship, described below, and each form can often be used to fetch the same data. Generally you can use the form that you prefer.

For example: "P1+2|Tagname", "~P1+2:Tagname", "K1+2:Tagname" and "K3:Tagname" all fetch the "Tagname" field from the same record.

To fetch data from a terminal group as child of a device card you must use a "Gn" relationship because the reverse of the "P1" relationship from the device would find the terminals, not the terminal groups. "G1+1:Tagname" and "G2:Tagname" will both fetch the "Tagname" from the same second terminal group record.

Special relationship codes

Code	Relationship	The related record:
P1:	Parenting	The tag record of the "parent" or "container" component of the main component.
P1|	Child	This shows the first child of a containing parent item, for example a cable's first core. The child relationship is signalled by the "|" (vertical bar) delimiter. If you need the second child you can index the children by an offset from the first ( P1 | = P1+0 | ) e.g. P1+3| is the fourth core of a cable. See also Siblings. This is a generalised reverse lookup and can be used for relationships other than P1 but that would be an unusual requirement.
~P1:	Child	This shows the first child of a containing parent item, for example a cable's first core. The child relationship is signalled by the "~P" indicating a reversed P lookup. If you need the second child you can index the children by an offset from the first e.g. ~P1+1: is the second core of a cable. See also Siblings. This is a generalised reverse lookup and can be used for relationships other than P1 but that would be an unusual requirement.
K3:	Child	This shows the third child of a containing parent item, for example a cable's third core. The child relationship is signalled by the "K". A "K" child relationship always indicates a child by a "P1" relationship. It cannot be used as a generalised reverse lookup. For a generalised reverse lookup, use "~Xn:" or "Xn|" described above. Note: Use T1:, T2: etc to fetch the terminals in a terminal group - see below.
G3:	Terminal group (child)	This shows the third terminal group of a device, for example a PLC card's third I/O channel. The terminal group child relationship is signalled by the "G". A "G" child relationship is used specifically for terminal groups. It cannot be used as a generalised reverse lookup. Note: Use T1:, T2: etc to fetch the terminals in a terminal group - see below.
R1:	Ratings	The ratings record for the main component.
C1: and C2:	Connection	Two terminal records to which a wire or cable core / conductor is connected. These connection relationships are always resolved from the core or conductor.
T1:, T2:, T3:, ...	Terminals in terminal group	Each device or instrument terminal assigned to this terminal group. Compare this to K1:, K2: etc which fetch the child terminals of an instrument, device or terminal strip. A terminal group is not the parent of the terminals, therefore the Kn relationship does not apply. Instead the terminal group has its own Tn link to the terminals in its group.
A2:	Association between components	The record of the associated component, e.g. an instrument, to which a device is associated. The A2: association is used between any types of "main" component: instruments, devices, terminal strips and I/O cards.
PJ:	Project Data	The one and only record of the ProjectData table - a global table from which you can fetch project-wide data without any requirement for a relationship to a component.

Sibling relationship - ~P1+2:

If the primary component to which a relationship refers has a parent, then you can fetch a "sibling" of that primary component from its parent (another child of the parent) by specifying a sibling number after the relationship (e.g. "+2") before the relationship delimiter (i.e. before the ":" or "|").

For example, if "~P1:" refers to a terminal from a terminal strip, then "~P1+2:" refers to the third terminal of that strip. "~P1+0:" refers to the first or primary component, i.e. the same as "~P1:".

The sibling number is particularly useful for reverse relationships, "Pn|", and "~Pn:", which are usually used to fetch child components such as terminals of devices.

Sibling ordering

Generally the next sibling will be identified in the order of the IDX column of the records. You have the option to order the siblings by their Tagname or by any column of your choice.

If you put a single 'A' after the sibling number in the relationship, then the next sibling will be identified in alphanumeric order by the Tagname column. For example: "~P1+2A:" will fetch the third child in name order. The same ordering can be applied to the "K" relationship, for example "K3A" will fetch the third child in name order, the same child as the previous example.

You can also specify your own choice of ordering column after the sibling number in the relationship. For example "~P1+2Function:" or "K3Function" will both fetch the third child as they appear when sorted alphanumerically by the Function column.

See also

Aliases