How to design an electrical wiring diagram - Page 1
Forum section: electronics / projects

author: lmagalhaes
author_rank: Contributor
timestamp: April 21, 2020, 11:57:25 am
content: Hi there,I'm developing a controller and have all the schematics, PCB files and everything done on Altium. But now, it's necessary to prepare documentation on how the controller connects to the other parts of the machine (sensors, electrovalves, heating elements, mains, etc). I've seen some electrical wiring diagrams done for assemblies with PLCs where the connectors are marked as Xx (X1, X2...) and it's pretty easy to follow. However, I don't actually know how to make that correctly and was wondering if there was any templates for Altium or other programs (free) that might do the job. Does anyone know a good program for that and have like a guideline on how to do this type of documentation properly ?Thanks

author: tpowell1830
author_rank: Frequent Contributor
timestamp: April 21, 2020, 01:39:06 pm
content: Hi lmagalhaes,I am a wire design engineer, and, the program that you are talking about is non-trivial, as it creates a netlist of interconnections, devices and parts. Each device has a reference designator as an identifier that can be created singularly or multiple times in a wiring diagram extracted from the same part information and is comprised of a sophisticated database. I am not familiar with Altium, but I have used a very sophisticated program for years in my job that is supplied by Siemens called Mentor Graphics Capital and it is very complex (and very expensive). There may be some free ones out there, but i am not aware of them.With that said, in lieu of such a program, you could create a netlist with a spreadsheet and accomplish the basis for the wiring diagram design by identifying each connector on your device and creating the pin to pin spreadsheet in its' simplest form of:FROM Ref Des PIN # WIRE Gage SIGNAL TYPE TO Ref Des PIN#Each of the above would be separate columns headings. Of course, as engineers, we want every detail of the design put into this spreadsheet, so you could add the left hand side connector part information from your device as detailed as possible and then, later in the spreadsheet, go from the opposite direction in order to identify the right hand side back to the original connector on your device. Also, you could add as many headers (columns) as desired in order to finely define this circuit. This would be your wire list and a diagram could easily be created from this information with the correct software and you would not need be involved (except for clarification).The other method, if your device is small (less than 500 circuits? maybe?), and if your signal types are similar or the same (such as MAINS, CONTROL, and/or RETURN), you could simply create a ladder diagram of your controller in the machine system, which includes the entire schematic design. This is dependent on how simple or complex your wiring will be. If this is all power and control circuits, this is what I would recommend. You could use AutoCad or any other flat drawing system to accomplish this.Wiring design is a multi faceted discipline and can be somewhat simple, as in the case of a ladder diagram, or very complex as in netlists and multi-cored wires with many different functional characteristics, depending on the signal types. I can't even begin explaining the complexities of designing wire systems in this format, on this forum. But this is a 10000 meter view of such a system.Hope this helps...

author: lmagalhaes
author_rank: Contributor
timestamp: April 21, 2020, 03:54:37 pm
content: Thank you for your answer tpowell. The goal here is to have a drawn schematic so people can correctly assemble the final device. It's not that complex, It's a couple of electrovalves and some heating elements and sensors for a small machine. It's not even to be used by engineers, only people on the assembly line to know where to connect the cables. But if those people are accostumed to a certain type of schematic, I'd like to accomodate to that and draw them a schematic that will be familiar to them and easy for them to understand, rather than throwing something together on Altium that I clearly understand but no one else does, you know ? After all, this documentation is for them and not for me.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: April 21, 2020, 07:10:11 pm
content: Yes, the "wire list" spreadsheet that I was describing is what our assemblers use to build the wire harnesses. An accompanying simple schematic is helpful in order to fill in the gaps, along with a BOM. The BOM is used/created by the manufacturing engineers to order materials and parts for the assembly.The harnesses that I design are very complex (aerospace), so the design that I give the assemblers is accompanied by requirements and specification documents so that the manufacturing engineers can sort out how to build the harnesses and train the assemblers.For what you are describing, a schematic diagram and a parts list will probably work, along with some assembly guidance from general assembly documents that are common to the industry, such as NASA.STD.8739.4 NASA WORKMANSHIP STANDARDS for aerospace, which is openly available for anyone to download and applies to the aerospace industry. You simply put a note on the diagram that "ALL WORKMANSHIP AND ASSEMBLY SHALL ADHERE TO THE LATEST VERSION OF NASA.STD.8739.4." For machine harnesses, perhaps a more industrial standard, which I am sure you can find with a quick google search. Also, industry "BEST PRACTICES" could be used instead of a named document, for your purposes.EDIT: You have to remember that YOU are giving the assembly group the requirements to correctly build your harness to YOUR specifications.

author: max_torque
author_rank: Super Contributor
timestamp: April 21, 2020, 07:29:05 pm
content: "Eplan" is pretty much industry standard for industrial automation projectshttps://www.eplan.co.uk/uk/start/allowing harness design to be done syncronously with the actual hardware design, building BOMs and harness pinout effectively for free as part of that process. Unfortunately, it's not "free" software, but their may be some similar "rip off" version that is?

author: WattsThat
author_rank: Frequent Contributor
timestamp: April 21, 2020, 07:50:17 pm
content: There was a post within the last month or so that provided a link to an Eplan like open source tool. For the the life of me I cannot find the link. It looked like a good tool, hopefully that person will be see this and post the link again.Edit: found it!https://qelectrotech.org/index.html

author: MTA
author_rank: Newbie
timestamp: April 22, 2020, 12:53:41 am
content: Try this:https://www.pcschematic.com/en/products/pcschematic-automation-electrical-cad-software/download-free-electrical-cad-software/