Upgrade from Siemens S5 to S7


Thread Starter

Chris Corne

For anyone who has undertaken an upgrade from S5 with 155u chassis, 948 processor, tons of ET-100 remote i/o to an S7 (possibly 400 series) with all profibus i/o, would you do it again? Or would you go away from the Siemens line altogether? Chris Corne Melt Shop Electrical Nucor Steel Arkansas (870) 762-2100 ext 239

Hakan Ozevin

S5 155U with CPU 948 processor is quite a powerful PLC and still manufactured. I would not upgrade it to S7. If you will make some additions, you can find necessary hardware from the shelf. If I would repeat the same project, I would use S5 again, since hardware drawings and software are ready. Hakan Ozevin

Donald Pittendrigh

Hi All I have undertaken a few of these upgrades, some retaining the old i/O and some replacing the whole PLC, if you can handle the S5 hardware and you replace with an S7, you are going to be a very happy person. You will have to convert the ET100 to ET200 but the change is simple. The S7 400 can interface to S5 I/O. Regards Donald Pittendrigh
Hakan, Yes you can still buy S5 products, but they are on Siemens mature list, which has been explained by the local distributors, means that for the next five years, we can only swap out a used part (defective) for a new part, no new projects (or simple upgrades) can be supported with S5. Their ET-100 (non profibus) line of remote I/O has been on the mature list for some time. We also use a couple of racks with 928 processors, and they are limiting us now with available program memory. We really do need to upgrade from S5!

Helmut Meissner

Hi All, I would change, if you have to do, all PLC parts of S5 and ET100. Our Siemens stuff in frankfurt told us it is possible for up to 15 years to get spareparts for the S5. It is also possible to get S5 part for new plants (we just build up a factory for portugal in S5). With the S7 you also will get problems in getting "older" parts. We used the S7-416 (with no DP), it is now out of stock and we had to change to S7-414-3 (because we need the memory for programs and data), same with L2-FMS CPs. On the other hand, we have good experience with S5 and S7 and would not change to other vendors. Greetings from germany Helmut Meissner

Hakan Ozevin

I think you are not correctly informed by your distributor. You can check the online catalogue of siemens from ad.siemens.de. You will see that: -CPU 948 -CC 135/155U -I/O modules of 155U -I/O modules and bus units of 100U are NOT mature products. You know that ET100U is simply IM308+IM318+S5 100U I/O modules. Thus you may only meet problems with IM308 and IM318 (6ES5 318-8MAxx), but this should be only a few percent of your project. You can still order these two units from "spare parts" division in Erlangen, Germany. If your distributor still insists on not supplying them, I can offer the parts from here, Turkey! (I mean products in original packing). CPU 928 case is something different. CPU928B with two slots width (6ES5 928-3UB11 or 6ES5 928-3UB12) is a mature product, that's right. But you can still order CPU928B with one slot width (6ES5928-3UB21). I just ordered and received a few months ago. I did not check for CPU928A, but it must be available also.

Sharad maheshwari


I think there is no need for you to replace the S5-155U CPU (948) as it is a powerful CPU and not a mature product. Rather I would suggest you to replace the ET100 with ET200M (IM153-1). In this case on the S5 side you will have to plug IM 308C instead of IM308A and use the S7-300 I/O modules.The communication between the IM308C and the ET200M is on Profibus-DP and the bus speeds can be upto 12MB. This is a very popular configuration and has no problems. May be later you could change the S5-CPU with S7-CPU. Siemens as a vendor generally is not a problem.
[email protected]