S7 200

[Guest Albert fanakapan]

Dear Siemens gurus Although I am an established programmer - mainly Mitsibushi Omron and Toshiba, I have never had anything to do on any Seimens PLC. A customer of mine has bought a second-hand machine with a S7 200 controling it. And it doesnt work correctly. Although most of the machine seems OK, there is a part of the cycle where the machine should slow down and stop on a proxy switch. The proxy is working and gives an input to the PLC but the machine crawls past the proxy - ignoring it. This faults the auto cycle and it has to be manually re-setup and restarted I have the software Step7 Microwin V3.1 but no programming lead. 1st question; which programming lead do I need? (cheapest/easiest to use) 2nd How do I upload the program to study it 3rd How do I monitor the program. 4th and - how do I alter the program and download the changes Any help here will be appreciated. I am even struggling with just basic ladder programming with the s7 microwin software. I cant even make parallel bits join with the line above. and perhaps another question - what are the bit letters I have worked out that I is input and Q is output but what are internal bits Does anyone have a s7 200 program I can study Thanking you in anticipation Albert

[Crossbow 295]

The programming cable you'll need is the 6ES79013CB300XA0. You can buy it from any Siemens distributor. Monitoring and programming are easy once you open the software and connect to the PLC. I've got some programming tutorials for the S7-200 that I can email you. You can probably find them on the Siemens website too.

[Guest Albert Fanakapan]

Thanks Chris Got the cable and hooked up. I had a little trouble getting connected though. Set all connections to standard but could not get communication. A quick fiddle with the dip switches on the PPI cable and the magic green flashing lights came on :) (set cable to PPI mode) Although there was plenty of the program I didnt understand (and the software) The lines of code I was interested in were nice simple bit logic. (no symbols though) I wrote the comments as I discovered what they were. I found the problem and now I am a hero :) On first experience, I like the software so I shall read more into the instruction manual TY

[Crossbow 295]

I've found the Siemens S7-200 software to be one o the easier and better written ones I've used. The S7-200 is a nice piece as well. But you might want to upgrade that old software to Step 7 Micro Win 32 v4.0, which was just released in the last couple months. The new software lists for $295, so you should be able to get it cheaply from an authorized distributor. It's got some new and better features...

[Guest M. de Vries]

Microwin is a lot better and easier to work with than STEP-7, I hope one day Microwin is also for the s7-300 CPU series. Flush STEP-7 down the drain.

[DesertDog 0]

I agree, I just used the 200 series for the first time recently and it is so much better than the 300's. It actually works like a normal PLC and the help is usually even relevant.

[Guest Marc Sinclair]

Most of my work is with this particular PLC. Our company was the first to integrate an s7-200 into a system in the UK. You don't say which model it is, the series 2 plcs like the 222, 224 and 226 are newer version of the 212, the 214 and the 216. There are also a couple of odd ones, the 215, which has a built in Profibus slave, and the 210 a tiny controller, programmable via eeprom units. The later models are of course faster, with more memory and commands, the software ought to work out what you can and can't do. The latest programming software is indeed v4 - be warned though, it only works with XP and Win2000 but v3.1 should be OK. Use the help and read the online documention (the s7_200 manual is available on the siemens website in pdf format ), it is all very good stuff. Download the tips and tricks, as these are in the form of simple projects with programs explained. All the documentation, the tips and tricks are supplied with the software, on the second CDROM. If you need some actual programs contact me on or offline. marc sinclair http://www.germainesystems.co.uk By the way, don't knock Step 7, it is a _very_ powerful language. The S7-200 does have an IO limit, although this can be mitigated by using ASI, memory is also limited and there is no PROFIBUS master. Do check out the CP243-IT which is a webserver module with ethernet, we use these a lot, instead of screens - you can set params and read status over a network - even write values to the PLC using java. We also put all our documentation on these modules in .pdf format, no more lost manuals or drawings!! - you can also send email, ftp data and even program via ethernet, much faster that the serial leads.

[Crossbow 295]

I think perhaps the reason people are quick to knock Step 7 is it is not like the older 'standard' ladder logic programming packages. It is very powerful, but for those who can't afford to attend the manufacturer's classes, it's really a bear to learn on your own. I agree it is powerful, but if there was a quick start guide or a 'here's how you do this in S7' that would give some of the new users a baseline to start from it would help. The S7-200 is more what people think of as a PLC. The S7-300 and S7-400 are more powerful, but I don't find many apps requiring large PLCs anymore. More often than not, people will use a couple small PLCs on a network. One benefit of this is there are multiple processors so sections of a process can run, where with one PLC, a single failure is fatal to the process. We've found many people who put local PLCs in small fan control panels and that way the fans can continue to run if the network or the master PLC goes down. Especially important in livestock applications.

[DesertDog 0]

In two years of exclusively using Step 7 I don't see anything it can do that GE, Mitsubishi, & AB can't do more easily. The only powerful ability I see lacking in the others is the ability to make your own commands. I also tend to find that the 300 series uses comparatively more memory and runs at a slower scan rate for similar applications. Just do a reusable indexed indirect addressing application to see how powerful Step 7 is, it's one simple command in GE.