Siemens S7 SCL-rookie

[Longbow]

Now, such a comment just begs for some details. I am interested in the differences between a 315-2DP and a 315-2PN/DP.

Hello JesperMP,

some weeks ago I must realize that the 315-2PN/DP is based on the 317-2PN/DP (Tricore) and is a lot faster than the 315-2DP which is based on the C165 (same as in 314C, 313C....). This is not stated in the manual, but open the box or do some measurements, and you will see it!

SIEMENS uses C165 platform, Tricore(317, 315PN/DP) and MIPS(319) Platform and ASIC (318, 400).
Every Platform need own Firmware has its own Bugs and differences in Code Execution:
Example: Firmware Update Changes for 315 2DP, 315 2PN/DP, 319 2PN/DP:
(Bad TAR Operation in 319, bad LOOP in 315 2PN/DP, bad "o" Operation in 315 2DP) Other Players in this market are not better, but don't expect SIEMENS to be way better than others!

The URLs from the Simatic.com page is to long to be displayed correctly here
(or more likely I'm not able to show it correctly ;-) )
Please go to Simatic.com -> support -> Software Dowloads -> S7-300 CPUs -> search for the Firmwareupdate and read the Changelog

 

[augenstern]

@ All!

Thanks to all for comments, suggestions and help!

Together with our customer we 'brainstormed' a little and finally changed the way we will realize the project.

We will use some DLL (libnodave or some other) which gives us acces to the PLC from a PC using ISO-overTCP.

That makes life for us much easier as I do not have to port our software from C to SCL and run it alltogether with our customer's software in the PLC.

Reasons for this decision were (among others):
- memory requirements: we can't foresee how much memory we need
- possible incompatibilities from one PLC to the other.
- possible side-effects when two different pieces of sw are run

If we ran into trouble the time and money effort needed to debug and fix the problem(s) would possibly be enormous.

So we took the "easy" way:
- porting the software from some CPU32 hardware to PC is quite easy and done within a few days. I will put the sw into a DLL and put some GUI around it so a basic frontend will be available.

- debugging and maintaining of the sw running on pc-platform is easy as well.

I hope the approach reading and writing from/to PLC will work with Vipa as well.

For this time I avoid using OPC but when I find the time (and my boss gives his OK) I will probably shift to the OPC solution.


Anyway: I will stay in touch with this forum, a lot of fine people here around!

 

[L D[AR2P#0.0]]

My suggestion is to continue the port as a learning exercise. What you will produce will be messy but, you will know an awful lot more about S7 and SCL. Throw away the first implementation and then start again.

Told yah

 

[JesperMP]

some weeks ago I must realize that the 315-2PN/DP is based on the 317-2PN/DP (Tricore) and is a lot faster than the 315-2DP which is based on the C165 (same as in 314C, 313C....). This is not stated in the manual, but open the box or do some measurements, and you will see it!
SIEMENS uses C165 platform, Tricore(317, 315PN/DP) and MIPS(319) Platform and ASIC (318, 400).

This is all very interesting information.
In Siemens list over instruction timing for the S7-300 CPU's there is no separate entry for the various 31x CPUs.
There are 4 different columns - for the L MW instruction for example it says:
312 - 0.8 us
31x, 147, 151, 154 - 0.4 us
317 - 0.1 us
319 - 0.01 us
Are you saying that the instruction timings quoted in Siemens documentation is not correct ?

 

[augenstern]

Hi, L D[AR2,P#0.0] !

L D[AR2,P#0.0],

you're right, it would have been a learning experience!

I already learned a lot of PLC (with the help of your's and the forum)!

And maybe I can use that knowledge some day ....

THX!

 

[augenstern]

What font?

....wrong font in the last post ....

 

[Longbow]

This is all very interesting information.
In Siemens list over instruction timing for the S7-300 CPU's there is no separate entry for the various 31x CPUs.
There are 4 different columns - for the L MW instruction for example it says:
312 - 0.8 us
31x, 147, 151, 154 - 0.4 us
317 - 0.1 us
319 - 0.01 us
Are you saying that the instruction timings quoted in Siemens documentation is not correct ?

Hello JesperMP,

All I know are the difference between 315 2DP and 315 2PN/DP (the rest of the manual seem to be quit good, but the complexity of modern PLC is extremely high and correct measurements of single command execution times in the 317(315pn/dp) or 319 or speed7 is almost impossible:
Example: Make a small Loop with repeating commands in 317: it is a lot faster than in the manual
Make the loop with more than 2000 Commands (you are falling out of the Cache) and you get the same values as in the manual.

Our Measurements for User Code Performance (no SFCs...) (mean over all categories):
3152DP: 19% of 318 Performance
315 2PN/DP: 42% of 318 Performance
317 2PN/DP: 131% of 318 Performance

There are also differences between different Firmware Versions (319)!
Very Complex this topic ;-)

 

[JesperMP]

Thanks a lot for these details, Longbow.
This means that a 315-2PN/DP is a better deal than one might think from just looking at the specs.
Btw. the 315-2PN/DP is our standard PLC for smaller controls, and 317-2PN/DP for larger processes.