Usage of OPC UA protocol in addition to (or instead of) Snap7
- As well requested by c.Betz a long while ago
Here the accoring CERN issue (cannot be seen from outside CERN, so I copied the relevant parts):
I recently learned that the newest Siemens S7-1500 PLC family has embedded OPC UA servers, which seems to be a more standard and efficient protocol than Snap7. It supports for example a subscription model which would allow us to get rid of polling in many cases. Find here a Siemens presentation on it: 4_Simatic_KHI_2019_OPC_UA_Server_et_Client.pdf
The Snap7 protocol works well but is very insecure, anyone with access to the TN and the libraries can read/write to any Siemens S7 PLC and wreak havoc. No need to know the DB-numbers, one can easily script a loop to overwrite all PLC DB tags with zeroes for example.
Could OPC UA implementation be considered, in addition to the existing Snap7?
Open source libaries whcih possibly can be used for it: