Siemens Certified Programmer Exam

[L D[AR2,P#0.0]]

I get the call options when I insert a timer into ladder.

[JesperMP]

Originally Posted by L D[AR2,P#0.0]

I get the call options when I insert a timer into ladder.

Single instance is the default selection, and thus if you mindlessly hit OK, then that is what you get.
IMO, Siemens should have let multi-instance be the default when you are programming an FB.
On the other hand a programmer must be proficient enough to know the programming concepts and the programming software.

Multi instance in STEP7 Classic is even less intuitive for the 1st time user.

[504bloke]

Originally Posted by JesperMP

even less intuitive for the 1st time user.

There is a lot of Siemens stuff that isnt intuitive

[TurpoUrpo]

Originally Posted by 504bloke

There is a lot of Siemens stuff that isnt intuitive

That might be perspective thing, Germans seem to have totally different intuition...

[Puddle]

Originally Posted by 504bloke

There is a lot of Siemens stuff that isnt intuitive

This is pretty much why I've chosen to focus on Siemens. Surely by the time I get my head round everything they do, anything else will be a doddle.

[Peter Nachtwey]

Originally Posted by TurpoUrpo

That might be perspective thing, Germans seem to have totally different intuition...

It must be a cultural thing. My name is as German as German can be but I agree with JesperMP. There shouldn't need to be a selection. The IEC spec doesn't have a case where there are two different types of FBs. If I have a FB for a motion controller, I should be able to define 8 motion controller FBs in an array if I want or simply add a time FB that basically should be allocated in what ever FB or program it is defined in.

I think the real problem with the old Siemens stuff is that a lot was defined before they really knew what they were doing or how to go about using FBs. The IEC spec kind of lays that out but it came out after how Siemens defined things.

[parky]

I sort of dissagree with you Peter, Siemens had FB's in the S5 days, I do believe that Siemens way of doing things was closer to the IEC than any other long before it was even thought of, in fact I wouldn't be surprised if the IEC (or part of it) was based on the Siemens system.
I do see some odd things instance DB's for data ? not sure why.
rockwell's answer to this was to almost completely use a new platform whereas many others kept compatability with the older systems take Mitsubishi for example, their GXWorks (or even GXIEC) can program almost all their PLC range in one package, FX & A range have been about for many years but you can still use the GX range of IDE's to program them. Siemens also had SCL as did Mitsubishi i.e. a structured type of language I believe this was availlable before IEC was implemented in earnest.
Rockwell are well known for extracting as much revenue as they can whereas others (although now seems are going the same route) have kept some backward compatibility even if this was for their benefit.
As for on-line changes to AOI's or FB's there are some problems to overcome.
If you change the interface of an FB that means the calling block also has to change, this poses a problem, most on-line changes are done (as far as the PLC is concerned) before or after scan for safety, it is unreasonable for the system to be expected to download, implement a couple of blocks within the PLC housekeeping routines. Siemens was one of the few platforms where you could download all blocks while in run mode, however, this had to be done in a particular order, the problem is if the interface of an FB is changed then downloading the FB before the modified calling block (assuming it takes more time than the gap between scans) will shut the PLC down as it is calling a function that does not match the interface of the block.
There are ways round this I suppose, i.e. download the blocks into unused memory, then at the housekeeping routine remove file allocation from the existing blocks & set the address of the new one.
The problem is if a programmer downloads a modified FB (interface data) but not the updated calling block, then the PLC will fault.
Most systems will not let you do an on-line change if for example an FB has been changed & the calling block has not. also most on-line changes have a limited amount of size for a number of reasons, one is that the time it takes to transfer a lot of data, the other is many platforms have to shift the code to insert the changes all this during none scan part of the PLC operation.
This obviously depends on how the different platforms operate.

[parky]

Ooopppppsssss: it seems I've crossed two different posts doh...

[JesperMP]

It is definitely a cultural thing with these deutschlanders.
The good thing is that there is usually a lot of thought behind the decisions being made. If you are thinking a feature would be nice to have, it is usually already there .. hidden somewhere deep.

Originally Posted by Peter Nachtwey

I think the real problem with the old Siemens stuff is that a lot was defined before they really knew what they were doing or how to go about using FBs

One must remember that STEP7 Classic is from a time when we were still using DOS or Windows 3.11. It is that old. And STEP7 Classic was a huge step up from STEP5, they essentially listened to what was lacking with S5 / STEP5 and fixed it. The way they did it was to add symbols to what was essentially still a PLC with absolute addresses.

When I first came from STEP5 and started programming AB PLC5, I was impressed with how helpful the manuals were, and how intuitive the programming software was.
You may think that PLC5 is clunky today, but then you haven't tried Siemens STEP5.
And I see other german software having the same issue (I am working with EPLAN now...). Teamviewer being the exception.

[parky]

Actually, in it's time S5 was very good. I loved to program in STL (fb's were only STL), if you got the right manuals the documentation (providing you were used to Assembler type language) were pretty good, what you could do was impressive. I think in STL Siemens had it, i.e. the use of brackets rather than the Japanese way of MPP, MPS OR LD etc. You are right though it's a cultural thing, also what you are used to, In the late 70's - 80's most of my work was on Siemens although did many others like AB, SqD, Omron Modicon etc.
Obviously documentation is always a problem in Germany there are many dialects, also something called technical German, even native german speakers did not understand that, I worked with many German people & got the impression that some technical german words did not actually exist, even people fluent in technical german struggled as there seems to be a culture of making words up if there is no direct translation for a particular way of explaining some code, one thing I remembered is a german word for floppy disk this was documented as something like floppyterian but was a little longer the actual translation was diskette in normal german. I worked with many german engineers, having conversations with them regarding some of the documentation on existing systems it became apparent that they struggled to interpret some of them one guy explained (or tried to) that often words are made up (extended) to explain an operation, this differs from engineer to engineer.
Asian documentation translations are definitely very poor, however, they are getting better.
As for IEC, if you read the documentation it always refers to function blocks so RW decided to call theirs AOI's, not that it really matters & I suppose how they are implemented may be a little different but I suppose its the same as most PLC mfgr's use N/O N/C whereas RW use XIC & XIO. how many times on here have you seen questions about that.

[TurpoUrpo]

Originally Posted by Peter Nachtwey

It must be a cultural thing. My name is as German as German can be but I agree with JesperMP. There shouldn't need to be a selection. The IEC spec doesn't have a case where there are two different types of FBs. If I have a FB for a motion controller, I should be able to define 8 motion controller FBs in an array if I want or simply add a time FB that basically should be allocated in what ever FB or program it is defined in.

I think the real problem with the old Siemens stuff is that a lot was defined before they really knew what they were doing or how to go about using FBs. The IEC spec kind of lays that out but it came out after how Siemens defined things.

Siemens had huge influence on the IEC spec too. There ain't really nothing that bad with having datablocks in the first place. The problem is that they never moved past that in proper way. They have been pursuing backwards compatibility - for obvious reasons, they don't risk upgrade business as the path to upgrade is easy.

About the "cultural" thing, when I say german I mean germans who behave like germans not like in the US (it seems) that people relate to their background even when they're kinda long past of any influence of that background.