@microstar and @James Mierkey The DMX shield(s) should be grounded at one, and only one, point; normally the chassis ground of the DMX source. Grounding at multiple points, such as within the shells of XLR connectors, is a definite No, NO as it leads to hum and interference inducing ground loops.Maybe I'm getting the term "ground" confused here, but in a DMX system pin 1 of the XLR should never be connected to the shell of the connector per Bennette's "Recommended Practice for DMX512". Quote from page 8: "The shield must not be connected to, or be in contact with, the shell or body of either the male or female connectors because chassis mounted connectors are generally connected to mains ground and this could cause problems with ground loop currents." (Itallics are his). In fact, some imported 3-pin cables do have pin 1 tied to the shell and this will likely cause problems in a DMX system.
Multiple ground points is BAD. Leaving the shield floating un-grounded is also bad.
Toodleoo!
Ron Hebbard