Number of networks in a function

Hi all,

I'm creating an S7 program for a S7-300PLC.

My question is: How many networks can be used in one function in FBD-language? Or is this just dependent on the cycle time of the PLC?

Thanks

I haven't found any limits yet. In my opinion you should try to avoid to much networks in one Function. Using more functions instead of one large one can increase the readablity off the software.

In my software the largest function consists off approx. 600 networks. (All the HMI alarms of the software, 1 network=1 alarm)

Wim,

it's not even depending on the cycle time of the CPU. If the number of networks you're using give you cycle time trouble, just change the watch dog timer value. The number of networks is (more or less) only depending on how much memory is available and the number of instructions per network.

I however strongly recommend not to put too many networks in a single function. Divide your program in functional blocks as is the installation/machine you're controlling with your PLC. Let each function control a functional block of the machine/installation. That way you'll find it much easier to troubleshoot.

Kind regards,

Thanks for your reactions!

The number of networks is limited by max allowed size of a block (<= 64kB). With shortest possible networks in LAD it gives roughly 16k.

max network

i have tried with cpu 313c-2dp.
it supports only 999 networks.

Hmm... Good point (to forget LAD and use STL).