Wich Siemens PLC, Memory, Performance ??

[userxyz]

In the company I worked for before I worked here, there was a standardisation on a CPU 315-2DP. (carpet factory)

Now I work for a machine-building company. The price is important now.

For a previous project I used a 317 PN/DP, why... because I project before that one had a 315 PN/DP and runs around 52ms. This last project was bigger, so I've choosen a 317 PN/DP, that runs on 10ms with this machine.

New project now:
64 I's
128 O's.

I was thinking about a 312 CPU, BUT it has only 32kB they say. And I was willing to place an MMC of 128kB...

I wil also use Graph in this CPU.

The HMI is an OP73.

Little machine with many I/O's in a step program.

The MMC must be giant enough to put the program on ?
When to choose for 32kB or 128kB or more CPU memory... ?
What's the difference between both memory's ?

How to choose the right PLC if the program isn't written, so you don't know how giant it will be...

Regards,

G

 

[JesperMP]

You cannot know exactly how big the program will be until the program is written almost finished.
It is totally dependent on the individual programmers style in programming.
You can make guesstimates based on your own previous projects.

If you do not use the Profibus port in the existing 315-2DP, then you can consider both the 312 and the 314.
Both 312, 314 and 315-2DP have recently been released in a new generation that is significantly faster than the previous generation.
I think the new 314 is faster than the old 315-2DP.
Unfortunately the PN CPUs have not yet been released in the new generation. I am awaiting this new PN CPU generation impatiently.

edit: About the size of the MMC card.
It is the work memory size of the CPU that is important.

 

[JesperMP]

By the way.
There are significant differences between the 312 and the 314.
The 312 only supports 8 modules in 1 rack.
The 314 supports 32 modules in 4 racks.
There are also differences in the number of Merkers and Timers.

 

[JesperMP]

Just thought of the IM151-8.
If Ethernet is important it is the lowest cost solution possible.
It has 128 kB work memory. The performance is somewhere between 1/4 and 1/2 of the current 315-2PN/DP.

 

[userxyz]

k

My choice at this moment is:

314
64 I card
2x 64 out card
terminal blocks for the 64 channel I/O cards

No profibus needed.
The IM151-8... how to deal with all that I/O, will it be cheaper then the 64 channel modules?

Just thought of the IM151-8.
If Ethernet is important it is the lowest cost solution possible.
It has 128 kB work memory. The performance is somewhere between 1/4 and 1/2 of the current 315-2PN/DP.

 

[JesperMP]

Not sure how ET200S i/o measures against S7-300 64-channel i/o modules with regard to the cost.
You should check it youself.

Myself, I would NEVER use such high-density modules. The use of separate terminal strip via cables and connectors is cludge if you ask me. I also try to avoid 32-channel modules.
Another advantage with ET200S is that you can match the number of i/o more precisely than when using high-density i/o.