What is the difference between Simatic Systems and the Simatic PCS-7?


Thread Starter

Conny Karlsson

Hi... I would like to know (briefly) the main difference between the Siemens Simatic PCS-7 system and the other systems in the Simatic range. All Simatic systems are to my understanding "Totally Integrated Automation Systems". So where's the differance? Thank you in advance for any answers...
I have used the Pcs-7 system for about a year. We are doing batch control for chemical manufacturing. The Pcs-7 system has add-ons for plc programming and HMI functionality that does not come with the Step7 programming and Wincc HMI packages. However, it is just an extension to those packages. The primary difference between the Step7 package and Pcs7 is the addition of high level programming and hierarchial plant represnetation. Both are much better than the standard FB/FC/OB programing provided by Step7. I would be happy to discuss the system in more detail with both pros and cons. I am a user and I do not work for Siemens.

fabian trowitz

theres no need to discuss these systems, because a small sps is about 1500€ (S7-315) and ist ok. often you don´t need a HMI. the pcs7 needs a S7-400 for working and a developer tool and has a HMI. it is important if you have complex processes. in my opinion are these two different things, not comparable.
Pcs7 is built upon the standard Simatic foundation of Step7 and WinCC. So if someone is interested in knowing what the Pcs7 is as compared to a non-Pcs7 Simatic solution then they are worth discussing. Yes the Pcs7 does use the S7-400 line of processors (which are not cheap) but if you have and application that is not tiny then it has some advantages. From a debug/support prespective for anything but a tiny application high level tools have sinificant advantages.

Hakan Ozevin

The main idea of PCS7 is to give the possibility of using standard PLC products with extention of software tools in order to maintain DCS needs. Siemens believes that this will result in economy, flexibility and power for process control, where Siemens had always market problems compared to their position in PLC sales. (They *may* be number 1 in worldwide PLC market, but I am not sure if they existed in top 10 list of DCS market, before PCS7). In PCS7, there are some software ad-ons to integrate HMI (WinCC) and process control software (CFC and others) that are intented to handle the functions in an easy way. The origin of the idea is coming from and old software of TI, called APT (Application Productivity Tool). Some believe that Siemens would not buy PLC part of TI if there was no APT. I did use APT in 1991 and I was impressed about it. I was even thinking that it was beyond that day's technology. I think the idea about PCS7 is very logical in theory, but I have doubts about the efficiency in practice. So, I am also eager to hear success stories about PCS7 system. Hakan Ozevin
As the so called "father" of APT I had a very hard time coming to grips with the concept of Pcs7. Considering that Siemens had essentially "killed" my baby I railed at the idea of using Pcs7. I looked for every reason to consider it a failure. However, the realities of making a living intervened and I found myself at a point of being asked (and expected) to take on a Pcs7 project and making it a success. We looked at the "out of the box" aspects of Pcs7 and found them lacking. But Siemens did make it extensible and there is considerable integration between the Hmi and the programming. What was lacking was a good set of "objects" like APT had and a good set of symbols like Pcs-osx (the Hmi developed by TI). Because Pcs7 is extensible (in a way similar to APT add-on objects that I develop and sell) we developed a set of object and corresponding symbols (valves, motors, control valves, command forms, tag details with trends, batch faceplates, etc). Alarming is also integrated between Es-tools, the plc and the HMI and that is a great feature because my process alarms are built as I build the control (pid, analog alarm, valves, motors, etc as I configure them). Also my SFCs can be displayed in the HMI and provided to the operator for monitor and troubleshooting (another very nice feature is batch automation) With this collection of objects the functionality of Pcs7 is quite good. We have been very very successful doing batch projects at my customer's site. I have found that I can do development quite productively. Now is Es-tools better than APT? Well it does have some features that windows provides that APT could never get to because of Siemens lack of willingness to continue with APT development. APT is still superior in my estimation when you can compare functionality to functionality. There are things that APT has that Es-tools does not have and vice versa. APt is truly object oriented and this is exceedingly superior to the IEc-1131 approach to programming. But given the fact that I am using Pcs7, I do like the things that we have added to make it a DCS like product. If Siemens would take the approach that we did with APT then Pcs7 could be made into a good product right out of the box. Anybody that has ever dealt with Siemens knows however that prevailing additude is that Siemens develops what it wants to develop and Siemens expects customers to buy whatever they sell. So getting Siemens to recognize what they could do to make Pcs7 very good is almost impossible. Pcs7 can be made to work very well with the right toolset and the right application methodology. Its just a matter of getting the right team when doing a Pcs7 project. John

Bryan Kowalchuk

As an experienced user of PCS7, what would you say are the biggest pros and cons with PCS7?

I've heard that the WinCC software portion has a tendency to crash alot, that the scripting is limited to 64K total for all scripts, that a number of errors that show up after performing an illegal action are still in german, and that
technical support is poor.

From the Step7 perspective, from the little I've seen, the SFC portion seems limited by the number of transition conditions that are allowed, without of course getting fancy and grouping conditions in a separate section of code. The CFB portion of it looks like it can easily become unruly. I like the idea of being about to create device/object blocks, like those seen in APT, but with the added feature of being able to tailor their functionality to what the project requires. One of the biggest issues I see, with S7 in general, is the general inability to make online changes without interrupting and usually stopping the processor. In a process where a momentary shutdown requires an 8hr CIP, this is certainly not desirable.

If you have any major issues that you are willing to provide, that would be greatly appreciated.

P.S. I have written PLC programs in APT for a number years now, and would be interested in talking further about the pros and cons of it as well.