Some failure rates (in hours) of PLCs below, with the source of the data. This includes spurious trip failures and failures that will prevent the system operating but will not cause the PLC to trip (unrevealed failures). Apologies for the format it is from a spreadsheet I have.
CPU 1.0E-05...
How do you calibrate or check the calibration of vessel weighing system. I believe you can hang test weights off them but how are these generally mounted and are the weights sufficient to make a serious change in output.
Any other info about loads cells would be greatly appreciated.