Dear experts.

I have to choose a PLC for the large project, where it will be used as a supervisor for other PLCs (S7-300). My main worry is that I will run out of work memory for my control program. Is there any concept, that can be used to predict the amount of memory needed for control program? Programming will be done on SCL. My current choice is 416-3 PN/DP, because it has a large amount of memory and built in PN port. Communication with other PLC's are over IE.

Hi,

can you elaborate more on 'Supervisor to other PLC' ?

What exactly will be it's role.. like controlling the plant thru these PLCs at downstream

or just calculating the efficiency of entire plant

or assessing alarm and events from other PLCs and initiate some actions somewhere.

Hi.

The roll of central processor is to control the plant thru these PLCs. S7-300 PLCs are doing some local calculations and communication with field devices, but the main control logic will be done on S7-400. Currently the central control is done on PC based system (high level programming language, not Siemens) and I need to select PLC, that will replace this system. 

Pitons,

to give you a solution we need to know the whole system. 

The best is to have a look in the  SIEMENS CONTACT DATABASE.

Search for technical consulting/Engineering Support in your country. They will have a look on your whole system and give you a proper solution.

regards,