I know that both Flowserve and Ruhrpumpen can provide feedback on the drill stem position within the coke drum as part of their overall cutting system. They can also assist you in retrofitting an existing system. Both of those systems work well. They also include a tensiometer on the cable to determine if the cutting tool has contacted the top of the coke pile. This can lead to unspooling the cable that can be a serious safety hazard.
While it might be possible to add these indications to your system independently, my recommendation is to have Flowserve or Ruhrpumpen evaluate and update your system. The probability of success is much higher with them being involved. Early attempts to add this functionality had significant reliability problems that have been worked out with the current designs.
