You want to use Modbus TCP/IP on your SCADA Modbus master to query information from the power meter, which uses an RS485 connection. Is that correct?
You can configure your TRB145 as a Modbus gateway.
How this works is that your SCADA system will send Modbus TCP/IP queries to your TRB145 and TRB145 will be able to query your power meter over serial according to the Modbus slave ID. TRB145 will receive a response and forward it over TCP/IP to your SCADA system. Slave IDs can be configured manually or obtained automatically from Modbus headers. Since you are using a cellular connection to establish a communication channel with TRB145, you will need a public IP address. This will depend on your mobile operator. Sometimes there are different APNs available that grant public IP addresses, but you need to consult your operator if you do not have a public IP address.
More information about Modbus Gateway can be found HERE.
A few words:
- Ensure that the 'Listening IP' is your public IP address.
- Ensure that the port is the same on the devices.
- Ensure identical settings are set on both devices. Baud rate, data bits, parity, stop bits, flow control.
- In IP filter options on the RS485 configuration page, add IP addresses that will be allowed to reach your Modbus gateway/devices.
- Modbus Gateway has to be turned on only in RS485 settings. If you are using Modbus Serial Master or any other options, please, turn them off.
I tested this myself with RUT955, but this is identical to TRB145.
Diagslave simulator software running as RTU Slave on a PC via RS485 serial connection to RUT955. Software configuration (command at the top) and the running window:
Next, RUT955 is configured to use a specific APN that provides a public IP address for my RUT955 mobile interface. For information on how to configure APN refer to the section 'How can I set a custom APN?' on the FAQ page.
RUT955 has the RS485 section configured and set as a Modbus gateway.
RS232, Modbus Serial Master, and other serial/ Modbus settings are turned off.
I used 'Poll Modbus' application on my phone to establish Modbus TCP/IP connection with my RUT955 using a public IP and request Modbus data from my Diagslave simulator software on a PC.
I was able to successfully read data from and write data to the RTU slave.