Multiple Comm Port issues

If used one at a time serial ports work fine with ScadaBR. If I plug in a second serial port and only have a single Modbus Serial datasource ScadaBR will transmit on both serial ports at the same time. This will make both serial data sources not return any data. I can not have more than one serial device plugged in at a time otherwise I will not get any good data from either.

Is this a known issue?


No, it is not an issue. It is because Modbus supports only one master (ScadaBR is the master and the RTU devices are the slaves).

You can use as many ports as you want, but each port must be a cionnected to a different network, with different devices.

Also, you can have up to 32 RTU devices for each serial network.

Thanks a lot for taking the time to reply fmunhoz. It seems to me that it would be better to just add more data sources when you wanted to communicate to more devices using aditional comm ports. This way you could use different protocols, baudrates, or protocol settings. This is how all the industrial communication drivers I have ever used have worked. At any rate, the way ScadaBR handles multiple comm ports does not work. Like i said, It does not matter what combination I use, If I have more than one comm port I can not get good data back from any comm port.

Once I get some more time I will try to dig in to ScadaBR and see if I can figure out how it all works and see if it can be modified.

Hello Fileark,

Usually, using multiple serial ports is not an issue. ScadaBR uses some layers to reach serial through modbus.

OS <-> JVM <-> librxtx-java <-> Modbus4J <-> ScadaBR runtime

We have some projects that run modbus on multiple ports (nodes and/or single instruments). None have shown the behavior you suggested.

Maybe checking on versions of librxtx and java? I really don´t know. But the logs may have a hint to whats going on. You could debug this personally by configuring the log4j properly.