Most basic DC motor controllers do rely on switching the 240VAC supply, but there are controllers that do have internal enable circuitry.

Sprint drives (I've just checked the 680i manual) have a run input, but they have the following warning -
WARNING. RUN is an electronic
inhibit function. The field remains energised, and all power terminals ‘live’. RUN must not be relied
on to ensure the machine is stationary during hazardous operations. Remove the power source to the
system.

Having had a quick look at a couple KB Electronics drives (KBIC and KBMM), they also have an inhibit input, but again they only disable the armature output, so the motor will still be live with voltage on the terminals.


Is there any reason why you can't use a relay as the main inhibit, as DC drives are designed to handle the input being switched regularly.