Dynamic IsoTcp to MPI gateway behaviour

Using the eWON as an ISOTCP to MPI gateway is really usefull when you have an IsoTCP software unable to build long TSAP request, but it's limited to one device.
see Use eWON as ISOTCP to MPI/Profibus gateway

To get around this limitation, some of us tried to dynamically modify the parameter IsoTCPGWNode by Basic (with GetSys/SetSys functions) to reach different MPI node (one at the time).

It works BUT we noticed a problem, some PLC have a limited MPI sessions number and each time you go on one destination, you open a new MPI session. Then, after a moment, the PLC doesn't accept a new MPI session and you will see some "MPI-Read fails" error in the events.txt.

Usually, unused sessions will be closed after a TimeOut, but on old PLC you need to reboot it.

Conclusion:  Using eWON to reach several MPI node by dynamically changing the IsoTCPGWNode parameter is functionning BUT, depending of the target devices, you will be limited in the rate of destination changes.