How to acquire data from Modbus TCP devices

[guangyuzhang]

1. Login MyEMS admin

2. Go to System Settings | Gateway Settings

3. Click 'Add Gateway' to add a gateway, click 'Save' then copy the ID and Token for configuring myems-modbus-tcp service.

4. Go to System Settings | Data Source Settings

5. Click 'Add Data Source' to add a datasource, the default tab is 'Data Source'

6. Select the Gateway created in Step 3, input 'modbus-tcp' for Protocol, input '{"host":"192.168.9.101","port":502}' for Connection, change the IP address and Port according to your Modbus device.

7. Click the 'Point' tab of Data Source Settings, select the datasource created in Step 6.

8. Click 'Add Point' to create a point.

9. In the 'Object Type' dropdown list, 'ENERGY_VALUE' is an incremental energy consumption value of parameter of a meter, 'ANALOG_VALUE' is time-varying "quantities" (voltage, current, etc.), and 'DIGITAL_VALUE' must have a finite set of possible values. The number of values in the set can be anywhere between two and a-very-large-number-that's-not-infinity. Most commonly digital signals will be one of two values -- like either 0V or 5V. Timing graphs of these signals look like square waves.

10. If 'Is Trend' is checked, the value will be saved to the historical database(myems_historcial_db)

11. In 'Address(JSON)' area, for 'modbus-tcp' protocol, please use the template below,
    {"byte_swap":true,"format":"<l","function_code":3,"number_of_registers":2,"offset":6401,"slave_id":1}
    'byte_swap' for Byte Swapping
    'format': refer to Format Strings

12. Once you have add all Gateways, Data Sources and Points, please update config.py under myems_modbus-tcp and then install and start the myems_modbus_tcp service. Refer to myems_modbus_tcp