OMRON HMI Screen Change Problem

[Gordo26]

Hey guys, I have an NSJ series OMRON HMI that I have an issue with. The screen number was set to #25 for a build status, two buttons on the HMI were linked to IO 41.00 and 43.00, upon pressing the HMI button the rung in the PLC program turns true and the corresponding MOV command executes, but rather than move #25 into D0(this location is used to change the screens, different values represent different screens), it moves #24 into D0. However, sporadically the MOV command would move #25 into the D0 register, but very seldom. I'm running system version 6.5 on the HMI and using CX-Designer version 3.2 software. Please note that in the very same screen with these two buttons I have two more buttons connected to IO 40.00 and 42.00 which successfully use a MOV instruction to change the screen to #16 every time the button is pressed. I would like any advice on trying to troubleshoot this problem, or anything obvious that I might be missing, I'm extremely new to the software so anything would be of assistance. Thanks for your time. Gord

[Andy_P]

Well, it sounds to me like you almost certainly have something else writing a value of #24 to D0 when you press your 41.00 or 43.00 buttons which you intend to write #25 with, and this is overrwriting the value you want. Hard to say for sure without seeing your code, but definitely check anywhere that you intend #24 to be written (if anywhere) and make sure that 41.00 or 43.00 don't appear there. I would check for duplications of your buttons in the program, and also check everywhere that D0 occurs too, to see what writes to it. Do you have any indirect addressing happening that may possibly write to D0? Indirect addressing errors can make for 'interesting' debugging sessions. Also worth checking: Are your buttons momentary acting, or alternate acting. I'm guessing they should be momentary, i.e. press = address on, release = address off. Are there any macros running behind either of the buttons or the screen page itself? A few things to check there, good luck.

[Gordo26]

Thanks for your help, I've just changed the screen name to #24 and it works fine, then I changed it to #28 and still worked fine, I'm not really sure what the issue might have been, could it be because of an older firmware on the screen itself? Just a thought. Gord