- Find out the modbus address and baud rate of ME237 by following instructions of the power meter and navigating in the keypad menu system of the power meter. In my example here the power meter is at modbus address is 1 and the baud rate is 9600. Connect the power meter over RS485 to the main subnet interface of T3-nano. Each device on the RS485 network needs a unique Modbus subnet address and we generally use address 1 for the master (the nano) but in this example we will set the nano to address ID 2.
- Connect T3-nano to Ethernet. You can use modbus poll software to confirm whether the connection between the two devices is reliable.Fill in the IP and port of T3-nano in the connection settings.
Enter the Modbus address of ME237. When the connection and settings are working correctly you will be able to see the Modbus data from the ME237 power meter on the RS485 subnet.
- Open the T3000 software, scan, and T3-nano will appear in the list.
- What need to do now is to poll some of the data from the ME237 with the T3-Nano with a small program. The program will read data over RS485 and store it in the VARIABLES table of the T3-Nano. For this example we will read the address and baud rate from the power meter. From the documentation of the power meter we see this is stored in addresses are 80 and 81 respectively.
Create two variables in the T3-Nano, give them a name and a range as shown below
Then head to the programming section of the T3-nano and begin a new program:
When I typed, I used the variable names VAR1 and VAR2. T3000 will automatically replace them with the labels you entered.
10 MADDR = 2.1.MB_REG80
20 MBAUD = 2.1.MB_REG81
Note: The first argument in MB_REG statement is a ‘2’ which is the panel number of T3-nano, not the modbus address. Both are 2 in this example which could be confusing, we will update this post to make things clearer shortly. The second argument ‘1’ is the RS485 subnet ID of the power meter. The third argument is the register number we want to read, 80 and 81 in this case which are the Modbus ID and baud rate from the power meter.
Next we will read the readings for the voltage, average current, and total power being measured by the meter and store the data in the INPUTS table of the T3-nano. The screen shot shows us filling in the names and units for the three values in the next available ‘input’ positions, IN1 IN2 IN3.
Here is the example program, we use the MB_REG_FLOAT command to read the volts, current and power values. Hit send when and assuming the syntax passes the program is sent to the T3-nano for execution.
Then you will see the data of ME237 on the INPUT page and VARIABLE page.
- Graphical interface
Refer to this post, you can make a graphical display page like the following
T3000 Webview graphic quick start
