Modbus RTU Over TCP

Hi good day to all.

I just want to ask if anybody tried using the “Modbus RTU Over TCP” driver?

Our setup on the plant (Ovens) is that we are using a 16bit RTU using RS323 Serial that is connected on the Modbus to TCP converter, then we used VxComm to our supervisory station using a third party SCADA software. Right now we are currently migrating to Ignition but we had difficulty connecting to the oven RTU, though the Device Status says that it is Connected, I still cannot see the Tags in the Quick Client. Not sure if this is because our “Modbus RTU Over TCP” is on trial mode or something, but I think resetting the trial is suppose to show the values on the tags for 2 hours.

I also want to add that my coworker also tried the configuration and managed to show the tags accidentally, unfortunately, he forgot the settings he done. (Below are the tags shown on his configuration.)

I’m not sure if I’m missing some other configuration or something, maybe a OPC Connections server I think.

Thanks a lot.

Right, there’s no such thing as browsing in the Modbus protocol, so the only tags you’ll see when browsing the OPC-UA server are those you’ve explicitly configured in the address map (click the addresses link next to the device in the gateway).

The address map is handy when the tags you need to address exist in contiguous ranges of memory and have a homogenous datatype.

The alternative is creating SQLTags manually, using the address format described in the user manual. You end up with item paths looking like this, assuming a device called ‘MyModbus’:


The final example there shows how to define a specific unit id instead of using the default of 1.

Either way you end up doing the addressing, you still need to actually know the modbus addresses and datatype of the tags before you begin.