Posted 1 Jul 2019 Dear all, the following error happened with me as following 1-power cut happened 2-rack with DO wasn't working "meaning no DO on plc module or from PLC but from function was active & some DO was blinking very fast" action I took 1-after more try change address for DO module from H/W configuration with spare DO "using Rewiring Option" worked well but I face the following error "i don't if problem was new or related to last action' error on counter module FM450-1 I/O access error and error on FC40 "System function for counter module" no change in H/W wiring in field was done any one need more data can ask DO & FM not on the same rack CPU416 Share this post Link to post Share on other sites
Posted 2 Aug 2019 yes it related. because " I/O access error " occurs when you trying to access to I/O´s that are not assigned to the CPU. you can get more info in diagnostic buffer. Share this post Link to post Share on other sites