What's the lowest model 1500 you'd recommend with an integrated OPC UA Server?
This may give you a hint of what is possible:
https://support.industry.siemens.com/cs/us/en/view/109755846
And you can play around with this:
https://perfdata.public.siemens.com/perfdata.aspx?version=34&lang=en
My estimate is that what is possible via an S7 connection on an 1511 CPU will need a 1517 CPU to achieve the same via OPC UA.
edit: If the data volume is very low, OPC UA will be OK even on a small CPU. So it depends on what is required in the actual case.
edit: Even on a high-end CPU, it seems that you will reach transfer times of approx 250 ms unless the data volume is very low. I use down to 100 ms for data that is used to visualize movements, and I want a smooth animation on the screen. This is not a problem for an S7 connection, even on smaller CPUs.
DigiWaste said:
we need an Modbus RTU connection to the Schneider SCADA system, and my client intend to use a Modbus RTU module (CM PtP) in the Siemens PLC to achieve that.
Who says that you 'need' that ?
If the Schneider SCADA is not completely outdated, then it should support some other protocols than Modbus RTU.
Today, Modbus RTU is very rarely used, mostly as the last option when nothing else is possible. I.e. to connect a modern PLC to a legacy device.
Modbus RTU is never used as the main data connection between a SCADA and a PLC.
It is like sending an important document by fax.
I would challenge the clients decision, and ask if either OPC DA or OPC UA are possible. What exactly is the Schneider SCADA ? Name, and version ?
edit: Do not be confused by the above discussion about the OPC UA server integrated into the S7 CPU.
The OPC UA server can be installed on a PC, either the SCADA PC or another PC, and then there will not be any performance issues.