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Read the following information in conjunction with the tasks required for Extract and organize data from PDMS.

Basic Principles of PDMS Specifications and Component Data

PDMS uses a general catalog of component data, which includes bores, dimensions, item codes, descriptions and Isogen SKEYs for every component available to the system. It also has a specification database that you use to create and store piping specifications, which reference a selection of components in the catalog.

Each line in a PDMS specification refers to an individual component. It contains the item code, or name, of the component, its bore(s), such as PBore0, PBore1 and so forth, and pointers to other data in the catalog, such as CATREF, DETAIL, MATXT, BLTREF, and so on. For more information, see Extract and organize data from PDMS.

Extraction of Data from PDMS

A PDMS macro called CatScan has been written to extract the data required to construct a catalog corresponding to a PDMS specification. CatScan reads the nominated specification and then accesses the catalog to get the required data for each component. For more information about using this macro, see CatScan Macro Listing.

Point Sets

Each component in a PDMS catalog has a point set, which defines its geometry and connectivity. Every point set has an origin (P0) and one or more other points, which are defined relative to the origin. Points can be defined in three ways:

  1. Axial Points (PTAX) - Defined as a distance along a defined axis (Paxis) from P0.

  2. Cartesian Points (PTCA) - Defined as X,Y and Z movements from P0 and therefore contain their own direction. The direction given for a PTCA is the direction of the connection leaving the point, not the direction between P0 and the point. It is not used by the software.

  3. Mixed Points (PTMI) - Defined as for a PTCA. The difference is not clear, but it does not affect the software.

So that they apply to all components of a given type, point sets are defined parametrically are made specific by applying appropriate values from a list of parameters held for the particular component in the PDMS catalog. For example, an inline component can have P0 at the center, P1 at the inlet, and P2 at the outlet. The point set extracted by CatScan might then be:

Pt type 1 PTAX
PDis 1 PARAM 1
Paxis 1 -Y
Pt type 2 PTAX
PDis 2 PARAM 1
Paxis 2 Y
Bore 1 PARAM 2
Bore 2 PARAM 2

A parameter string of 100, 50, 200, 37.12, BW, results in an overall length of 100 + 100 = 200 with the inlet and outlet bores both equaling 50. Alternatively, this same component can have a point set where P0 coincides with P1 at the inlet and coincides with P2 at the outlet. If the parameter string is 100, 50, 200 37.12 BW and Cartesian points are used, the point set extracted by CatScan would then be:

Pt type 1 PTCA
PDXYZ 1 0 0 0
Direction 1 Y
Pt type 2 PTCA
PDXYZ 2 0 TWICE PARAM 1 0
Direction 2 Y
Bore 1 PARAM 2
Bore 2 PARAM 2

The previous example illustrates the use of the TWICE operator, which is interpreted as Value = 2 * the value following. The overall length of the component is 2 * 100 = 200. I-Convert can interpret a variety of operators, which are used to define point sets as follows:

  • PARAM n Assign the value of the nth entry in the parameter string.

  • nTIMES m n * m where n is a constant and m is an expression, such as PARAM 1.

  • SUM n m n + m where n and m may be constants or expressions.

  • DIV n m n / m where n and m may be constants or expressions.

  • DIFF n m n – m where n and m may be constants or expressions.

  • MULT n m n * m where n and m may be constants or expressions.

  • TWICE n 2* n where n may be a constant or an expression.

  • DDANGLE the change of direction in the component in degrees.

  • DDHEIGHT the change of direction in the component in degrees.

  • DDRADIUS the change of direction in the component in degrees.

  • TANF n m n * Tan(m / 2) where n and m may be constants or expressions.

  • SINF n m n * Sin(m / 2) where n and m may be constants or expressions.

  • COSF n m n * Cos(m / 2) where n and m may be constants or expressions.

Format of the Extracted Data

CatScan Macro Listing produces a data set for each component as follows:

Spref /P100/DJEBHAC:PM

Detail /DRE-CU----

Skey REBW

Rtext ECC RED S10 BW

Stext ---BHAC-----

Ttext unset

Matxt /M1SFE---

Xtext SS A403-WP304W/304LW DUAL MARKED

Ytext DJE---------

Ztext unset

Catref /PRE0A-AUPM

Gtype REDU

Bltref Null

Bdiam Null

Leng Null

Noff Null

Parameter 203.2 101.6 152.4 52.35 219 114.3 30 BWD BWD

Pt type 1 PTAX

Paxis 1 -Y

PDis 1 0

Pt type 2 PTCA

Direction 2 Y

PDXYZ 2 0 PARAM 3 -1TIMES PARAM 4

Pt type 3 PTAX

Paxis 3 -Z

PDis 3 0

Pt type 4 Null

Paxis 4 Null

PDis 4 Null

Bore 1 PARAM 1

Bore 2 PARAM 2

Bore 3 0

Bore 4 Null

This data is interpreted as follows:

  • Spref - Specification reference, or SpecRef. It is comprised of /<Spec Name>/<Item Code>. Using the previous example, a component with item code DJEBHAC:PM in specification P100 has a SpecRef of /P100/ DJEBHAC:PM.

  • Detail - A pointer to the detailing text in the catalog. The text is held in up to three variables: Rtext, Stext, and Ttext. Together, these make up the first part of the component description. Each variable can contain either a string, an empty string or the value unset. If CatScan Macro Listing does not find a valid string, it outputs the value Null. The software ignores unset, Null, and strings that contain only blanks. Detail also points to the Isogen SKEY for this component, which is output complete with its end type.

  • Matxt - A pointer to the material text in the catalog. This is held in up to three more variables--Xtext, Ytext and Ztext--which are treated as detailing text and appended to the Rtext, Stext and Ttext values.

  • Catref - A pointer to the catalog. This pointer enables you to find the Gtype, which defines component type, a parameter string that contains a list of parameters applicable to this component, and a pointer to the point that defines the dimensions and bores of the component. The point set is interrogated to return the values for each point in the form previously described. (Pt type n, PDis n or PDXYZ n, Paxis n or Direction n, and Bore N). For more information, see PDMS Technical Information.

  • Bltref - A pointer to the bolt table, which returns the diameter (Bdiam), length (Leng), and number of bolts (Noff), if appropriate. This is used to build the bolt table for automatic bolt allocation in I-Convert.