Modbus TCP disconnection and no reconnection [SOLVED]

I’m experiencing a problem with ignition v. 7.9.1 ( also recreated on 7.9.4 ) regarding a Modbus TCP connection. I’m trying to estabilish a connection between Scada and an AC500 PM590 CPU from ABB ( also tested with a PM573 ). The onboard ethernet card support something called OMB_Time, and after looking on internet and on ignition forum, I understood that is closing the tcp connection after a while when no data ( 1000 ms ) is sent from the Scada. So i declared some variables, without using the automatic addressing function, and set a direct-scanclass with 250 ms of polling time. It’s now working, i don’t have anymore connection and disconnection on gateway status page, but when i disconnect the cable from the plc the only way the connected to the plc again is changing the scan class time, i.e. from 250 to 251 ms. If i change the modbus tcp driver properties or if i restart the OpcUA module, the device status is changing from disconnected to connected every couple of seconds. Do you have any suggestion please?
Thanks in advance, Andrea.

after a complete reset of the PLC, I downloaded the new OMB_Time parameter with a greater value ( 30000ms ). Now everthing is working fine, probably the reconnection time/retry of Ignition was almost the same of the PLC ( default is 1000 ms ) and there was an overlap of connection/disconnection. I hope this can help, best regards, Andrea.

Thanks for posting your response I have been struggling with the same issue.

Happy to help you. If you’re going to use also ABB v3 with integrated OPC UA you can encounter problem when exchanging a huge number of variable ( i.e. 50k ). The solution ( thanks to Inductive Automation support ) is to reduce the default value of “Max Per Operation” and “Max References Per Node” to 100 and 100.
Regards, Andrea.