I am trying to find a clean method to use the standard conveyor start/stop functionality to keep products from going out of range in my application. Sometimes, I use a checklimit which is upstream of the work area exit limit. As soon as the GetItmTgt is executed with the checklimit option, all products between the checklimit and exit limit are ignored for the conveyor control and products move out of range. I have experienced similar headaches when two item types are on the conveyor and using the ItemType switch causes the other items to be ignored and move out of range.
I have used PLC based workarounds to cover up for these problems, but I am looking for a way to get a clean signal directly from the robot/pickmaster since my workarounds usually lead to a new range of problems.
Any ideas? Help would be greatly appreciated.