Master Control

[daxtojeiro 0]

Hi all, I have an issue with a program that has been written by someone else and I can't seem to get my GX Developer software (8.62Q) to work on it. Basically when I go on-line for the first time and download the program to the laptop I can see the [MC N0 M300] instruction, then under it there is a vertical AND with N0 beside it. If I save the file or modify it that vertical gate disapears and the program no longer compiles. [MC N0 M300] stays. Im guessing I have a setting ticked wrongly, or something like that, but I can't figure it out. I can not even add a vertical gate, so Im lost on this. thanks for the help Phil

[kaare_t 155]

Are you sure the program was downloaded with GX Developer, and not GX IEC Developer or GX Works2? If possible, provide som screenshots or the whole program....

[daxtojeiro 0]

Hi, Thanks for the reply As far as I know the program was originally written in GX, the company has folded that did the work Im afraid. I did try it in GX IEC and it didnt look great, so it wasn't written in that. Heres a screen shot. The missing AND gate is between line 44 and 49. thanks again, Phil

[kaare_t 155]

Not sure what can cause this, not too familiar with GX Developer. In any way, there should be a terminating instruction (not sure what it's called in GX Dev.) so the MC knows where to end.

[Rodney 21]

as Kaarte_t has said you will have to have a terminating instruction so the MC knows were to end. The instrucion would be MCR N0 with no contacts ptior to it. you will also see a contact in the vertical power line when in monitor mode N0 M300. Rodney

[daxtojeiro 0]

Hi, thanks for the replies. There was a vertical contact in the power line striaght after the instruction, when I down loaded it. As soon as I edit it, save it or send it back that contact dissapears and I cant seem to add it back again. The compiler then fails as it doesnt see the contact and causes an error, so its not sent. Ive ammended the screen shot to show what I mean, thanks, Phil Edited 14 Mar 2012 by daxtojeiro

[Rodney 21]

Phil In my message yesterday I mentioned that you can see the vertical contact in the power line when you are in monitor mode. I can see from your screen shot that you are in write mode. You will also see it in read mode. Regards Rod

[nehpets 19]

Are you writing the closing MCR N0 Instruction? Steve

[kaare_t 155]

Again, not an expert on GX Dev. but you could just add MCR below the MC line, this should cause the same behaviour. However, according to your drawing the MC doesn't have any function since the Return is placed directly after the MC so no code is executed between the MC/Return. Basically I would simply try to make a backup of the project, then delete the whole MC instruction and try to download....

[Crossbow 295]

Manual JY997D16601 will cover the MC and MCR instructions, as well as all FX3U instructions. Recommend you start there.

[daxtojeiro 0]

OK, thanks for the info. If I go from Write to Read mode the instruction comes back into view. Thats great news but I have no idea why it does that. I will try to upload it to the PLC in read mode and see how that goes. The trouble is the machine is 100 miles away, so its not a 5min job. thanks for the help Phil

[daxtojeiro 0]

Thinking about it, the error said something about the length from the MC instruction was too long. I assumed as I couldnt see the vertical contact that was the issue. But I'm guessing that the problem isn't that. It is indeed that there are too many lines of code from the return instruction. If that is the case then all I need to do is move the return up a little and add another MC instruction using the same logic. Sorry for the misunderstanding, I miss read the issue and was looking in the wrong direction. I will pop down there and try this thanks Phil