Posted 21 Jun 2018 We have a QSeries PLC. Q25HCPU. We also have a PLC program. We found that the address registers (also known as device addresses) attain a z-value added next to it - automatically over time. We are not sure why this is the case. Nonetheless, when these values get added (by the PLC - not the engineering software), some of the functions in the PLC doesn't work. We found that by formatting the CPU, and reloading the program, allows for the system to work again (temporarily) for a few weeks, up until this problem occurs again. This problem occurs across various CPUs (eliminating the potential for hardware problems. These z values can be seen when a program comparison is done. (see attached file). The questions become; 1. What is the function of these values? (why does the PLC add them? 2. How can they be permanently removed? Share this post Link to post Share on other sites
Posted 22 Jun 2018 (edited) This are index registers. They are not added by the PLC!!! they are part of your program. So if you have D15Z0 . this means that if the vallue of Z0 = 14 Then the device being used is D29 (15+14). Looking at the devices being used it looks to me that the original project uses a FB and you are looking at the compiled code Edited 22 Jun 2018 by Gambit Share this post Link to post Share on other sites
Posted 9 Jul 2018 Thank you for the reply Gambit. Thing is, the table above is attained via a program comparison. The table on the left shows the code as is on GX developer. The table on the right shows the code as is found on the CPU. The additional Z values are not being added by the user, as can be seen by the left table. Share this post Link to post Share on other sites
Posted 10 Jul 2018 Are you sure you are using GX Developer and not GX IEC Developer ? Share this post Link to post Share on other sites