Siemens S5 with Softnet OPC Server


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I have a S5 PLC with an ethernet card which is read by Siemens IE Softnet OPC Server. I can access all the data except reading a bit from a data block.

For an input bit I use IX0.0 and for an integer from a data block I use DB37INT52.

How do I read a bit from a data block without stripping it in SCADA. I have tried DB37X52.3

Any help much appreciated.


Kriebel, Rick

I recall facing the same problem. If memory serves, datablocks can only be accessed in WORD or DWORD format. I, Q, and flag-memory can, however, be read in as bits (only written to as bytes, though). We use Simatic Net v6.0 with WinNT. Maybe this is different with v6.1 and
I have now stripped out the bits in SCADA.

Thanks for the info.

I now find that I can't read the data for a counter either as it takes in all the bits so returns the wrong value. I have to strip this out with shifts or move the value to a datablock.

I'm sure that it would not have been difficult for Siemens to make such basic features work with some simple code in either the comms processor or the OPC server.

Thanks Again

You are right it was not difficult for Siemens to do this. The S7 solves all those problems. Sometimes it is much easier for a company to create something new than to try to make something old better.