Thanks for help
Hi
Found the problem and fixed it. Just for curiosity what it was, The problem was that we have a ring roller and the operators would set the wall size, the height size and what ID (interal diameter) they wanted, these were set via bcd thumbwheels. The setup uses 3 encoders one for wall one for height and one for the OD (over diameter) it uses the formular of (2xwall)-OD = ID (no calculation is done for height). we have 4 bcd displays showing Height, wall, ID, and OD. To calibrate this system we have a calibration ring set at 100mm high 50mm wall ,400mm ID and 500mm OD, so all we do is put the ring in the machine and hit the calibrate button and it moves the set values of the ring into the plc then to displays.Apparently the following problem is ongoing. Every time the machine moved into the ring it was losing 10mm - 50mm eachtime on the OD but if you move it back mark a spot and drive it forward then drive it back you dint lose anything. So i thought ok maybe the shafts lose on the encoder and its gripping up close to the machine so we pulled the encoder assembly down ok nothings wrong with it its all tight ok ill eliminate the encoder could be that its faulty so when i disconnected encoder from coulping i noticed it had a sleeve on it with no obviouse grub screw or keyway, the fitter who was helping me said thats ok, so we put new encoder in put the sleeve onit (and i still didnt like that it was a tight fit but nothing was holding it) reassembled the assembly and tested it, but the problem was still there, the day earlier i changed the plug wiring back to a junction box, ok maybe the cable in the flexable track is breaking,so i ran a temp cable back to the plc from the junction box, tested problem still there (a bit of hair pulling now) ok the problem now has to be the Encoder card its mising pulses sometimes in the forward motion. Posted the thread about swapping card on the weekend (no reply by monday morning) so decided to go with my gut feeling, powered down, pulled old card out set dip switches and put in the spare counter card, tested, FFS the problem was still there ok ill go back to my other gut feeling the encoder assembly grabbed the same fitter and we went back to the encoder, he kept saying its ment to be like that theres nothing wrong with it, and he left again so by now im a little frustrated so i held the assembly and moved it back and forward (theres about a 2-3mmm play in the assembly due to loose coupling that bolts the encoder assembly to the machine) and what do you know it started to loose 2-3mm each time i moved it forward and backward AHHA went back and got the fitter and said if im wrong you can have my car, i asked him to couple the sleeve to the assembly by using a adhesive (which you almost need two trucks to tear apart) put it on reassembled it and tested, HOORAR perfect every time now, place old counter card back but kept new encoder as old one was 6 years old anyway. RULE ONE-Never trust a fitter
