Tag: opc-ua

Every Beckhoff controller already speaks ADS. OPC UA is a licensed server on top. Measured from the controller’s own figures: reading natively by address barely registered, up to 2500 values every 10 ms. A busy OPC UA server put its work in the PLC task. Resolving names in the runtime on every read cost up to 46% of its CPU. A look at what the OPC UA license buys, and where each way of reading puts its work.

How you ask a Siemens PLC for data matters more than which protocol you use. Reading the same hundred values off the same controller, a client that groups its requests is a hundred times faster on Modbus and five to fifteen times faster on S7Comm. That is larger than any difference between the protocols themselves. A measured look at what protocol and driver choice costs a PLC, a network and your budget.