Maximum number of the Program cycle organization blocks(OBs)

Hi guys,

I am using PLC s7-1500 ET 200SP CPU 1510SP-1 for my project and I have encountered on the problem about the maximum number of Program cycle OBs of the mentioned CPU. I created many OB to separate functionalities and to get more readable code. When I created the 51st OB I noticed that after loading the code to PLC one of these 51 OB is not active(not the last created). Functionality of that OB does not work. When go online and activate watch, I can see that whole OB is shaded(dimmed).

It seems that I exceed the maximum number of OBs? But I found in the data sheet for the CPU that maximum number of Program cycle OBs is 100. Now I do not have an idea about the reason for such behavior. Pleas for help...

Hello magicstreber,

why do you use so much OB's?

It's easier to program functions and combine there at a other FB/FC and so on.

Please tell us a little bit more 

• why you need so much OB's
• what do you want to do
  maybe there is a suggestion to use not so much OB's
• few information that the user of the forum can understand your challenge

regards
CaOd

Hello CaOd,

thank you for your reply.

I only wanted to have more clear organization of the code. In my so big project there are so many machines which I should control and for each machine I created separate folder within Project tree with appropriate global data block(DB) and organization block(OB). Because of that I have so many DBs and OBs. Maybe, this approach is not so good, but anyhow, based on the info from the data sheet it should be possible to have max. 100 OBs.

I can easily reduce total number of OBs, but I want to resolve this issue with more experience people on this forum, including you.

Of course, I am using FC/FB for reusable parts of the code.

Hello magicstreber,

so much OB's are not necessary.

It's easier to use a FB for one machine and call them at one OB.

You should program your logic not in a OB, it's for organization your functions.
The logic should programmed at a FC or FB.

Please move your logic to a "normal function".

Your solution works:

OB1
OB123 (machine 1)
OB124 (machine 2)
OB125 (machine 3)
....

It's easier to do the follow

OB1
   FB1 (machine 1
   FB2 (machine 2)
   .....

You have also a good overview about your single machines.
Furthermore you can use a the FC/FB also the languages SCL and not only KOP or FUP.
Then can you also use "general" functions for more than one machine.

regards
CaOd

I created all OBs in a regular way, without copying and with assigning  number automatically.

SIMATIC ET 200SP 6ES7510-1DJ01-0AB0  V2.1.0