S7 - Tips and Tricks for FM352-5

Has anybody out there had much experience with the FM352-5 High Speed Boolean processor.

I'm going to have to use one for the first time and would like to be forewarned of any potential peculiarities, in particular with regard to consequences of the parallel processor layout.

I've got (and read!) the handbook - I'm looking for the sort of simple but deadly weirdoes that you don't find in the handbook!

Thanks in advance

Roy

as i have written to you in my last reply

as i have written to you in my last reply,
you can find anything about Siemens by

http://www.ad.siemens.de

bye

Thanks, but I've got all the Siemens info, what I'm looking for is the practical experience with the quirks of the beast, which you don't find in the handbooks - and usually not in the FAQ's either, in my experience!

I have worked with FM modules before but not that particular one. I can offer Siemens support info specific to that module...lot of info including update time etc.

http://www4.ad.siemens.de/-snm-0135...view=4000003&viewLevel=6&wttree=cs&jumpto=278

I've worked with the 352 Cam Controller before, and it is an awesome product. I don't know why it isn't used more.

It has been a few years, so I don't remember many particulars, but I do remember that I became frustrated very quickly with the canned Siemens functions that were shipped with the module, so I wrote my own functions. Once I figured out what all the values in the DB meant, it was a piece of cake. I took a quick look at the pdf file, and the 352-5 seems very similar to the 352 that I used, so I can offer bits of help as you get familiar with this thing. Have fun.

Thanks once again, it's not exactly what I was after, but it did bring up some intersting bits of information that I would have needed to cover later.

Given my luck with keywords, that would probably have led to another thread!

S7Guy, you're posting arrived while I was answering rsdoran.

My requirement is to synchronise 21 Trigger signals with delay times of 1 - 2000 ms. The customer would like accuracy of the delays to be 10 µs, I've promised him 100µs. Judging from the specs it should be doable, but it looks like being an interesting exercise for the first acquaintance with the beast!

My former fellow coworker coerced my
boss into buying the FM352-5 module instead
of using a FM350-1. For our application
the 350 worked just great. Well after he
quit I got stuck with the 352's. They do
work fine also. However do to the time you have to invest in getting them to work its not worth it. For simple counting or tracking applications stick with the 350.

Well, it's been a long hard slog, but we got there in the end.

As I suspected, all the problems were the typical little niggles, which are obvious when you're aware of them, can but take ages to identify on your own. So for the benefit of anybody else who finds themselves struggling with this beast in the future, here are the worst of the nasties to look out for.

The first problem you're likely to hit is that having created your first program and stored it then downloaded it to the FM, the FM goes into error with a consistency fault. This one is a classic case of read the manual and do exactly what it says. Now this is not unusual, but there is a sneaky little catch out there waiting for you. Since I don't know how to paste multiple pictures into a posting, here's the relavent bit out of the manual. The key bits are points 4 - 7, in particular 6 & 7.

OK, now we have a look at the programming panel which you access by right clicking on the FM in HW-Config. It's all nicely laid out and the temptation to go:

Step 2 - 3- 4 - 5, work on your program and save it, do the syntax check (not really necessary for simple programs), compile the program and load it, is irresistible!

Resist ! Go back to the last post -

step 4, Compile the Application

Step 5, SAVE & COMPILE the Application in HW-Config!

Step 6, From Simatic Manager download the program blocks AND system data to the CPU.

Step 7, OK NOW you can load the program into the FM.

That cost me about three days - and the Siemens Hot-line couldn't help either. As I said in another thread, it's sometimes the simple problems that are the killers!

Oops, forgot the Piccy.

Here it is.

There's another little point to be aware of - in the manual it says, if you aren't using the Encoder inputs for an Encoder (you can use them as further digital inputs, in that case) you CAN delete the Encoder entry in the Declaration part of the FB. If you aren't using the Encoder inputs DO delete it - otherwise you'll get spurious consistency faults which you can't pin down - that one was courtesy of the Siemens Hot-Line!

OK, now for the next one that cost me another couple of days - once again, the Hot-Line couldn't help, although I suspect if they'd hit upon the idea of asking me to e-mail them my project, they would probably have found it fast enough. Unfortunately they didn't, they just wasted about half-an-hour on the telephone.

This concerns the parameterisation of the FBs for Normal, or Debug operation and in particular the parameters for the CPU_In and CPU_Out DBs (for those just reading out of casual interest, these DBs are used to channel the communication between the CPU and the FM352-5). As you can see, the inputs are entered as DB5.DBB0 and DB6.DBB0. The fact that you MUST use this format and not just DB5/6 or DB5.DBX0, etc., is not emphasised anywhere, but, as they say, it is in the manual!

Those were the worst problems, the next question - was it worth it. To that the answer is a resounding YESSS !

On my little test programs I'm generating delay times of 10µS up to 2 Secs, I'm getting synchronisation better than 2 µs - ON A PLC!!! Admittedly this is a very simple small program which fits entirely into the 12 phases of the 1 µs cycle. The real program, which is much larger will undoubtedly spill over several cycles, but I'm still hopeful that it won't deteriorate much. I'm certainly convinced that not only am I going to beat the 100 µs accuracy that I talked the customer into, with a little bit of luck I'm going to beat the 10 µs accuracy he actually wants. The Trigger delays were originally planned to be handled by a specially built "Black Box", which would undoubtedly have cost a large multiple of the 850 € that the FM costs.

So if you need really high speed response in your next project, don't forget this baby - by the way, that goes for you non-Siemens people as well, the FM352-5 can also operate completely autonamously, so you can easily integrate into another system to deal with the high speed part of the job.

One point I forgot to mention, while it's not a fault in the normal sense, it can be a serious irritation and if you're the conscientious type, you could finish up wasting a lot of time chasing a fault which isn't there.

When the FM is in STOP, the red SF LED is always on - so don't worry about it. It doesn't matter whether the STOP is caused by switching to STOP on the front panel or by removing the TRUE signal on the "RUN" input of the FM logic, the fault LED is on and in the block condition the Internal Fault is active - ignore it!

Hey Roy, I'm glad you are getting good results with that card. I got amazing results on the process I used it on, and I don't understand why it isn't used more. I think it's just so tricky to get set up for the first time that some people are hesitant to try it.

It's not just tricky, it's a nightmare, especially if you're on your own, or like most people under tight time constraints. If it hadn't been for the fact that I had so much time on this project I'd have been panicking, in fact towards the end I was starting to get a bit uneasy as well, because I expect to be able to start commissioning the first module in a couple of weeks and I wouldn't half have felt stupid if I still wasn't able to trigger it then!

The problem is that they are such silly little things, that unless you're extremely lucky with who you land on the hot-line, you're not going to get much help there either. Although on the whole the Siemens hot-line is pretty good, I've only had it happen one time that when I got onto them with such a typical beginner's problem, that the guy on the other end of the phone new immediately what was wrong.

Anyway, that's why I thought I'd write my experiences up here in such detail, so that the next guy who has to take his first steps with the beast will get some useful input when he searches here - hey not just here! We make the first page of Google as well - that's got to be good advertising for the forum!

Roy,
thats 1st class work.
I also make how-to documents when I have to do the same thing a year later.

If you could assemble it all together in a PDF and put it in the downloads section, then there is a greater chance that people will find it also in the future.