The handover moment is the moment when the project is least being drawn. The engineer gives the panel into someone else's hands: the fitting crew, the client's maintenance crew, or the next generation of himself. The question at this moment is not "where is the drawing?"; the question is "what is the package like?".
By package I mean the documents that go with the drawing. Without the BOM, no order can be placed. Without the terminal schedule, no wiring can be done. Without the cable schedule, no cables can be pulled. Without the I/O list, no PLC program can be tied in. The drawing is inside all of these documents; but the drawing on its own is only one part of the package.
The package is often not a single one
In reality most handovers are not made as a single package. The drawing circulates as a PDF in email. The BOM is in a spreadsheet in the office. The cable schedule is a photocopy, or does not exist at all. The lists were produced from a revision of the drawing that comes before, and nobody remembers that.
The person taking the delivery has to work out that these pieces belong to each other. He looks for a terminal number in the drawing and does not find it; because the drawing has gone one revision forward. He looks for a cable number in the schedule and does not find it; because the schedule is from the older revision. Every inconsistency wears down the confidence of the person taking the delivery a little.
The question "which one is the final one?"
When the pieces of the package are scattered, the most frequently asked question is "which one is the final one?". The question itself is the problem. In a package there is exactly one final version; if there is not, the package is a pile of documents contradicting each other.
In EupCAD the project is a single file. The drawing, the device data, the terminals, the cables, the PLC I/O data, all of it is inside the same file. The question "which one is the final one?" ends in the file itself: the file is the final one.
The reports are produced from the file
The lists of the package are produced from this file. The BOM from the device record, the terminal schedule from the terminal data, the cable schedule from the cable data, the I/O list from the PLC data. None of them is written separately, none is copied from the drawing.
That means that no document in the package can be older than the others. The source producing the lists is the same source as the drawing. When the drawing changes, the list is produced again; because it is not written in two places, one of them cannot be forgotten while the other changes.
A report row goes to the drawing
The connection between the documents of the package is not one-way. In EupCAD's reports pane, when you open a row, you can go to the page that row belongs to. Touch a row in the terminal schedule and you jump to that terminal in the drawing. Touch an address in the I/O list and you go to its counterpart in the drawing.
This is a feature that makes the work of the person taking the delivery easier. While reading a list, to see where a row comes from in the drawing, you do not open a separate file; the row calls the drawing.
The contents of the package: seven lists
EupCAD's package has seven lists, and the reader of each one is known:
- BOM — the purchasing desk. Part number, maker, quantity, description.
- Device list — the maintenance crew. Every device on one row: tag, function, page, rating.
- Terminal schedule — the wiring. Strip, number, type, inner/outer labels, cable.
- Cable schedule — the pulling crew. Number, type, cores, from, to, length.
- PLC I/O list — the programmer. Address, symbol, comment, module.
- Wiring list — the audit. Every tie on one row: from which tag to which pin, with which cable.
- Page index — everyone. Page number, title, section, scale.
All seven lists are produced from the same file. All are downloaded at the same time. None of them can be older than the others.
The I/O list: the programmer's rows
The PLC I/O list is the narrowest but most critical list in the package. Four things in every row: address, symbol, comment and module. The programmer reads the row and knows what that address corresponds to. The module column says which card the address is on.
This list is the proof that the PLC program matches the drawing. If the address in the program is the address in the list, the program is tied to the drawing. If it is not, one of them is older than the other.
The wiring list: the inventory of the wires
The wiring list shows every cable connection in the drawing on one row: from where, to where, on which page, with which cable and conductor. From the tag at one end of a terminal to the pin at the other end, the inventory of the wires.
This list is for audit. An auditor answering the question "is this circuit really tied this way?" does not walk the drawing page by page; he answers it in one row of the wiring list. The list is not a readable summary of the drawing, it is the drawing itself, only in table form.
PDF and SVG: the sharing formats
The shared form of the drawing is PDF or SVG. PDF is the format to be printed on paper and circulated by email. SVG is the format to be zoomed and inspected on screen. Both are exported from the drawing layer of the project; they are not drawn by hand as separate files.
That is the sharing not detaching from the source. The PDF shared is the state of the drawing at that moment; when the drawing changes, a new PDF is produced. The old PDF does not take the place of the new drawing.
The rule check is the last gate of the package
Before the package is handed over, it goes through the rule check. Address conflict, short circuit, protection mismatch, missing core in the cable, terminal duplication, unnumbered cable; each of these appears in the report before it reaches the gate of the package.
The handover is made with a clean report. If the report is clean, the person taking the delivery has a small chance of finding an error inside the package. If the report is not clean, the error is caught in the office; not on site.
The package going to the field is a file
The physical form of the package is also important. In EupCAD the project is downloaded as a single file; the drawing, the data, the reports are all inside the same file. If the drawing is to be shared, it is exported as PDF or SVG. The lists come down as CSV; each one opens in a spreadsheet.
That is what goes to the field being the same as what is in the office. The person on site does not work with an old PDF circulating in the office's email; he works with the package the office produced, up to date.
A handover is not where the drawing ends
An engineering project does not end when the drawing ends. It ends when it is handed over, when it can be read, when it can be held in the hand of the next person. The package carries this last step.
The engineer who gives only the drawing gives half of the package. The engineer who gives the whole package hands over the work.