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PCOM - Questions ( Consistency and Ethernet )

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Hello All

2 Questions:

1.) PCOM Consistency

When exactly are PCOM - Requests executed by the Operating System ?

Is this done at the end of a program cycle so if f.e. more MI's are written, data is always consistent for the whole program cycle

or is it possible that data is changed DURING a program cycle ( Interrupt driven, ... ) which leads to inconsistency of data for the program ?

2.) PCOM via Ethernet

How much Client Connections ( to TCP Port 20256 ) can be made at the same time ?



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1. The PCOM requests are exceuted once per cycle and if the communication buffer can contain all the requested data it will be consistent.

If the requested data is too large and the communication buffer cannot contain it all then it will take more than one scan to excute the request and then it can lead to inconsistent data.

2. If you are using TCP then only one client can be connected at a time to a one socket.

Unitronics Ethernet card offers 4 sockets that means you will be able to communicate with 4 devices over TCP at the same time. Each one of the sockets can be configured independently to protocol, port number and client or server.

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