How MBOC is operate?

[IgorK]

Hi all! Is anybody know, how MBOC is operate in details? (for GX IEC Developer v6.10) What's the difference between MBOC and SBOC? I known very little about it. And i can't find detail information. In www.MitsubishiAutomation.com' knowledgebase, i find such reference: ... if you set MBOC to 4K, the maximum amount of steps for additional program size is 1024 steps in every of 64 blocks. What is the blocks? Who knows? I have some problem, when i trying to execute online program change. My program is about 7000 steps. System area for MBOC is 4K steps. If i adding some code (size is less 1024 steps, without FB) to begin of my program, online program change executed successfully. If i adding some code (size is less 1024 steps, with FB) to begin of my program, online program change is fail. I get the message: The online change differences of the main program is too big, limit 64 blocks! However, If i adding some code (size is less 1024 steps, with FB) to end of my program, online program change executed successfully!!! Why??? Thanks for you replies. Edited December 9, 2009 by IgorK

[Glumglum]

The online change limit is different from PLC to PLC. Witch kind of PLC are you using? If you want to change the the allowed online program size go to the menue "Extras"- "options" and you will find Online change there. There you can increase the number og steps tranfered online. You also might have to increase the system variables to increase the online change size.

[IgorK]

I use the folow PLC : Q series, Q02CPU. I attempted to increase additional program size in Project options->Online change from 500 to up 2000 steps, but it did not effected... How may help me, increasing of system variable number? Edited December 9, 2009 by IgorK

[kaare_t]

Try increasing the value to 10000 (instead of 2000). If your existing program (the existing code in the PLC) has used all, or almost all, system variables then you will need to increase the "System Variables" area so that the new code (the one you are trying to download to the PLC) will have enough variables to assign. However, if you are completely sure that you have enough System Variables then you do not need to change that area.