KSS 8.3.34, Robot using the A7 motor for E1, and the A8&A9 motors together (master/slave) for E2. Using ProfiNet with basic ProfiSafe (no SafeOp).
My problem is this: one of these axes is vertical, carrying a very heavy load, so for safety the drive mechanism for the axis has an external electrically-actuated braking system, that needs to work in parallel with the robot brakes. Whether the External axes will be kinematically integrated is still up in the air, but at the moment there is no plan to configure them Asynchronously.
This is the first time I've run into this situation with a KRC4. I did it years ago with KRC2s, and usually wired the external brakes to "spare" contacts on the K1 relay, or (in one case) had the SPS monitor the E1 bit of $BRAKE_SIG and open/close the external brakes in concert with the E1 motor brakes. An imperfect solution, but it worked well enough (as long as the SPS was running 
)
So, I'm wondering what my options are on a KRC4. I could use the SPS $BRAKE_SIG trick again, but I can't help but think there might be a more elegant and reliable solution out there. Whatever I use, it has to work in Teach or Auto, for playback and for jogging. While I could just link the external brakes to $PERI_RDY, ideally I'd like to leave the External Axis brakes closed if/when only A1-A6 are in motion, so I'm not burning amps holding the vertical axis motionless for hours at a time. So I'd like to be able to link a particular external brake to a particular external axis.
Anyone have a creative solution they'd like to share?
