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General wiring standards

To achieve reliable operation of the UCC MMI and the CMM host computer, the following should be observed:

  • Scale readhead signals, reference marks and error signals should comply with EIA RS-422A. It is recommended that each readhead has its own screened cable and that these cables are kept well away from electrically noisy wiring.
  • All opto-isolated inputs and outputs should be separate from other connections to the UCC MMI controller, so that the CMM electrical system is kept isolated from the circuitry within the controller, with the exception of the 0 V reference and protective grounding.
  • All signal cables MUST be screened and all cable screens should be connected electrically to the cable connector's metal shells.  Cable screens should only be connected to the protective earth (via the connector shell) at the UCC MMI end, and not directly connected to the CMM protective earth.  This is to avoid earth loops.  However, the protective grounding must be continuous between the controller and all other equipment in the installation.  All cable connectors should be secured to the UCC MMI by the connector jack screws.
  • See also the installation instructions supplied with other Renishaw components in the system, i.e. probes or probe heads etc.  Particular attention should be paid to the screening and earthing methods of the cables carrying signals from probes.

NOTE: The UCC MMI electronics 0 V rail is connected to the overall ground plane at a star point within the UCC MMI.


Before beginning the installation of the UCC MMI check the following items:

  • Ensure that all connecting cables, test equipment and software are available
  • Ensure that the CMM measuring scales / readheads are correctly installed and are functioning
  • Ensure that all the CMM status and limit switches etc. are correctly installed and have been function checked
  • Ensure that all power has been removed from the CMM and the host computer