The local Siemens distributor claims 80% of our current S5 program file (written for 928, 946/947, and 948 cpus) will convert to S7. Does anyone have any experience of what does/does not convert? Chris Corne Melt Shop Electrical Nucor Steel Arkansas (870) 762-2100 ext 239

 

It all depends on your existing S5 software. Commands using relative addresses cannot be converted (there are no relative addresses in S7). Complex commands like "DO" cannot be converted. FB calls should be matched to the new System Function blocks. If you do not have these, the whole program changes to S7 100%. There is a specific manual for S5-S7 conversion. Ask it from your supplier or download it from Siemens web site. By the way, why don't you give the S5 program to your supplier and ask him to convert it for you? He can tell you how much he succeed. You can meet some problems, but in any case, I believe that it is easier to convert an existing S5 program than writing it (for any PLC) from nothing. Good Luck Hakan Ozevin

 

Hi All Program in the S5 dealing with datawords and induirect addressing do not convert well or not at all. Standard function blocks for example for analogs or multiplication of 16 bit numbers, don't convert at all. The standard ladder logic stuff is about all you can really depend on. Regards Donald Pittendrigh

 

Hi All, the converting is only doing easy networks and simple Data-operations. Indirect adressing, manipulations on S5-Code, etc. doesn=B4t work. For your peripherie you also to change data handling (analog, serial, L1-bus, etc.) Greetings Helmut Meissner

 

Hello Hakan, sorry but I think just the opposite way. Obviously the choice depends on the kind of application and the extent of the existing S5 program, but I would take a deep look to S7 and its new features before deciding for a simple conversion of an S5 program to S7. Rewriting all or part of an application using the new S7 programming concepts is more efficient than adapting old S5 code. The result is a better structured and well documented program, easier to understand and maintein. regards Luca Gallina - tecnog -

 

I agree with you, but the assumption is using the existing S5 program almost exactly as it is. We are applying both S5 and S7 systems and advice our customers to continue to use S5 not only if the PLC program is the same, but also if the plant has full of S5's and no S7's. Applying S7 is certainly easier for the software people, but you have to consider the maintenance people as well, looking at the existing spare parts, software packages and knowledge gained in servicing the PLC's. Hakan Ozevin