The pinout is the electrical definition of a D-Sub cable. It should remove ambiguity, not create it. A production-ready pinout identifies connector view, contact numbers, source-to-destination mapping, no-connect positions, and shield or chassis treatment.
Start by labeling the connector view
State whether the drawing shows the mating face or the wire/termination side. Rear views can appear mirrored relative to the mating face, so an unlabeled sketch is a common source of reversed wiring.
Add End A and End B labels and keep those labels consistent across the drawing, BOM, test record, and packaging.
Use a pin-to-pin table
For simple assemblies, list End A pin, End B pin, and signal name. For complex cables, add conductor color, wire gauge, branch name, shield instruction, and notes.
Mark unused positions explicitly as NC. A blank cell can be interpreted as missing engineering data, while NC shows that the open circuit is intentional.
Separate signal mapping from contact numbering
A signal such as TXD can appear on different physical pin numbers when you use two different connector formats. For transition cables, map the signal function and the physical contact at each end instead of assuming equal pin numbers.
This is particularly important for DB9-to-DB25 serial assemblies and for proprietary industrial equipment.
Document crossovers and jumpers explicitly
If transmit and receive are crossed, or handshake lines are looped or cross-connected, show the exact connection. Do not use only the words ‘crossover’ or ‘null modem’ when the equipment requires a specific handshake arrangement.
If the cable contains internal jumpers, resistors, or other components, place them on the wiring diagram and test plan.
Add shield, drain, and chassis instructions
A shield connection should not be hidden in a note such as ‘shielded cable’. State where the shield or drain terminates and whether it bonds to the connector shell, a dedicated contact, or another point defined by the system design.
The cable manufacturer should reproduce the approved grounding design rather than decide it during assembly.
Turn the pinout into an inspection document
The same wiring table used for engineering can become the basis for continuity testing. This is useful for OEM production because the approved drawing and inspection record refer to the same contact map.
Revision-control the drawing. If the equipment pinout changes, the cable revision should change with it.
Final check before you approve the specification
- End A view and numbering
- End B view and numbering
- Pin-to-pin/signal map
- NC positions
- Jumpers
- Shield/drain/chassis instruction
Avoid this shortcut: Leaving connector view unlabeled; copying a generic pinout; omitting NC positions; and hiding shield or jumper requirements in informal notes.
Continue the specification
Your next checks may include DB9 RS232 pinout, straight-through vs crossover vs null modem, and DB25 partial-pin cables. Open only the guides that match your equipment and project stage.
How BespokeCable can review the wiring requirement
For a device-specific cable, you can send BespokeCable the equipment models, the pin-to-pin map, and a verified sample when documentation is incomplete. The published customization process moves from inquiry and specification review to quotation, sample approval, and then production, which gives you a clear point to resolve wiring questions before a batch is released.
Turn your checks into an RFQ
Send BespokeCable your equipment models, connector details for both ends, approved pinout or verified sample, finished dimensions, shielding and mechanical requirements, quantity, and sample-approval criteria. You can then review a defined assembly instead of relying on a generic D-Sub description
