Siemens S7_HMI OPC driver: What is HMI adapter?

[Donald]

We/I have to set up a HMI communicating with a Siemens S7-300 PLC and I am currently determining PLC and PC hardware requirements.
Our preference is to use simple serial comm and threrby avoid having to install a Profibus card. I believe this limits our choice of OPC driver to the Siemens S7_HMI which the documentation says communicates through a Siemens "HMI adapter". Unfortunately, our Siemens distributor is unable to help as to what this device is and I had little luck on Siemens website.
Any pointers would be most appreciated.

[Khalid]

yes, the Siemens S7_HMI driver is meant to be used with a Siemens HMI adapter, which converts MPI to RS-232. This dapter is not the same as the MPI cable. It is a separate adapter the user has to buy from Siemens. The part number of the adapter we have is 6ES7-972-0CA11-0XA0 (SCPLN307900). However, Siemens changes its part numbers, so this may no longer be a valid part number. You need to check with Siemens for this.

Also, note that the S7-HMI driver works only at 9600 baud due to some restrictions placed by the Siemens' HMI Adapter.

Hope this helps.

Khalid 🙂

[Donald]

Thanks, Khalid.
That is the part number I finally got from a couple of other sources (although there are newer (?) versions with different 6ES7-972-OCAxx-XAO numbers which might do the same job) ... I also have been told that it's been renamed to "PC adapter".
Given its reliance on RS-232 and cost, I'm ending up going with the NI/Applicom Profibus card after all.
Thanks again.