Siemens acting as a Modbus server to Ignition

I was reading through the posts and noticed that the OPC UA with the Siemens 1500 tends to put some overhead in the plc, besides the s7 driver that ignition includes, and the OPC UA , can the communication be through Modbus TCP ? the PLC talking Modbus to ignition?... can the OPC UA overhead be solved by creating different OPC UA servers (different PLCs) ? How many Datablocks are OK for the PLC to handle in OPC UA ?

Yes, with this module:

If the 1500 plc can become a server itself, why would it need a middle man ?, shouldn't it be connected through ethernet ?

You asked about the PLC talking TO Ignition. If you use the PLC's OPC server, then the PLC is being talked to FROM Ignition.

There are limits and limitations in the Siemens on-board OPC that annoy some users. Having another path, in the other direction, may be useful.

(The linked module is a Modbus implementation that supports RS-232, RS-485, raw serial over ethernet, and Modbus TCP--also ethernet.)

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