KEPServer to Siemens S7400

[NZ_9888537]

Hi Experts, 

I have connected few PLC (Siemens S7-300) in our plant and now on progress connecting PLC (Siemens S7-400) to Kepware.  There is no issue on S7-300 communication and value reveive. Happy it works all well.

For S7-400, communication are ok however value received from PLC are different. all datatype (word,float,bool etc) are different value than PLC. i tried changing byte type (little and big endian), but value still different.

To test further, i do tried with SCADA which on same network, no issues on value received.

Need your advice.

[pshashipreetham · Accepted solution]

Hi @NZ_9888537 ,

Based on your description, here are a few areas to review:

1. Data block addressing and structure – the S7-400 might store values in a slightly different layout than the S7-300. Double-check that the PLC's data blocks, offsets, and data types match what you’ve configured in Kepware.

2. Data type mapping – even though you’ve tried changing endianness, mapping Siemens data types to Kepware data types might need review. Ensure the conversion settings for words, floats, and booleans align with the S7-400’s data format.

3. Communication parameters—Verify that the network settings (such as connection timeout, rack/slot numbers, and addressing) are correctly set for the S7-400. Sometimes, small discrepancies in these settings can lead to misinterpretation of the data.

4. Firmware or driver differences—Since SCADA can read the values correctly on the same network, compare the settings and driver configurations used by SCADA with those in Kepware. If possible, replicate the SCADA configuration in Kepware.

These steps should help isolate whether the issue is with the PLC's data layout, the conversion settings in Kepware, or the communication parameters.

Thanks,

[NZ_9888537]

Hi Shashi Preetham,

basically, our network consist of two plc ( .25.1 and .25.2). previously i configured kepware as below.

IP : X.X.25.1, CPU slot 2

IP : X.X.25.2, CPU slot 2

screenshot above earlier shown that X.X.25.2 are taking data from X.X.25.1 . im not sure why. so after changing PLC module setup and X.X.25.2 to CPU slot 3 at kepware, it works well.

so i would conclude that #3 advice are the solution for my case.

Thanks again Shashi Preetham for your reply and advice.

Note:  for kepware, selecting driver > siemens TCP/IP and model >either wrongly choose S7-300 or S7-400, it still can work : )