Signal assignment

We are currently developing a program to help optimise the assignment of electrical signals to connector contacts.

Our Signal to Connector Contact Assignment Program (SCCAP) has been demonstrated to a number of designers and safety engineers and has generated much interest and lively debate. We expect SCCAP will be ready for release mid 2013.

The problem

Companies that design safety critical systems often use connector planform drawings to show the assignment of signals to connector contacts. Signal assignments and the drawings currently have to be generated using tedious, time consuming manual processes with coloured pens. The design rules usually require certain signals to be grouped together where, for example, the signal wires are twisted or shielded. The assignment process is especially difficult when sensitive signals have to be separated from others with guard pins in the surrounding connector contact positions.

Due to the enormous number of potential solutions, this is a challenging problem both for the designer and for a computer program. For example, the theoretical number of ways of assigning 85 signals to 85 connector contacts is 2.82 * 10128. Even if a computer program were able to check 100 million assignments per second it would take longer than the age of the universe (estimated at 4.35 * 1017 seconds) to analyse all the permutations!

Since July 2011 we have been experimenting with various computer programming techniques and have been developing the SCCAP program. The program works in a similar manner to the HarnWare Cable Lay option in that it generates a number of solutions, ranked into order. The user is then able to select a preferred alternative or alternatives.


Input for SCCAP is from a pin arrangement (connector planform) and signal table drawn in Visio. Using HarnWare is the quickest way of generating the necessary connector planform drawing. The HarnWare connector database contains 22,000 planform layouts. For other connector planforms it is possible to use the drawing for a similar planform and, in Visio, adjust contact positions and to add or delete contacts, etc.


SCCAP can:

  1. Achieve substantial time savings.
  2. Remove the manual drudge and make signal assignment optimisation more accessible and interesting work.
  3. Achieve more optimised designs.
  4. Save space and weight in cases where SCCAP is able to assign signals to a smaller connector while adhering to the design requirements.

Please contact us if you would like further details and a video showing SCCAP in operation.

Circular connector Signal to connector contact assignment program

SCCAP accepts as input connector planforms drawn by HarnWare or by using Visio.

Signal to connector contact assignment program

The signals and their design rules are read from a table drawn in Visio by SCCAP.

Signal to connector contact assignment program

SCCAP uses the above input data to automatically assign signals to contacts in the connector planform according to the specified design rules and constraints.

Signal to connector contact assignment program

SCCAP can save assignment data to file.