Reducing Program Memory usage in S7200

Hello all,

Im working on Purified water s/m & distribution plant. I m using S7200 plc alongwith Beijers Eterminals for various plants.

S7200 plc CPU224 has 8kb program memory & i almost utilised it fully for my application, now i have to introduce few additional interlocks in it.

Some of my friends told me to use subroutine for repeated logic,
this will save memory, but i found out writing sub routine & calling it no. of times uses same amt of memory in my program.

Plz guide me


Thanx to all
with regards
Sanket

I'm not familiar with the S7-200 range, but you should upgrade to a CPU with more memory.

Subroutines (SBR) in S7-200 can be used in two ways:
- not parameterised (this will not save any program memory)
- parameterised (this sure can save program memory)


This is how you can make a parameterised Subroutine:

1)First make a subroutine (SBR) with local variables (#naam)
You can use IN, IN_OUT, OUT and TEMP Variable types

2)Then you can call your subroutine several times in your user program.
Each time with other PLC addresses

PS.: This is similar to S7-300 (“normal” FC’s and parameterised FC’s)

Good luck

Hi Sanket

There is a method to increase the amount of memory available to your program from 8192 bytes to 12288 bytes, though you loose the Run Mode Edit facility. You need up to date versions of the PLC and I think version 4 of MicroWIN. Can't try this myself as I am still on MicroWIN 3.2, but as described in the manual you go to View / System Block, Select Increase Memory and then download the updated program to the PLC. Let me know if it works, it might entice me to upgrade MicroWIN.

Bryan