bringing this topic back up, i caled in and spoke to a bunch of different venders, and based on all the information we are going to buy the laser distance sensors....we have a demo sensor that i have already set up and is reading perfectly! thank you again okiepc for a step in the right path, now a have been programming this for just 2 days, i have most everything set up to a point, than i realized i had forgotten about slanted blocks, also i was to understand the operator for now was going to be telling the machine what size block was going through...i have a PanelView600 hooked up to a SLC 5/03, the way i had it written was the operator was to punch in what size block was comming into the measuring machine, the plc would than input the tolerance specs, and if it met within the range would pass or fail, now they tell me they dont want the operator interface, so i have about 200+ lines of code to be reworked, wanted to see if there was an easier way of doing this,...our blocks range from sizes 4" to 42" and can either be straight or sloped, if sloped the low number comes into the measuring machine first than the high number. im thinking now of useing limit test instruction but how can i achieve this for the slanted blocks? maybe im just thining too deep. any help would be appreciated