sdm_modbus is a python library that collects data from Eastron SDM single- and three-phase kWh meters over Modbus RTU or Modbus TCP.
Supported devices:
To install, either clone this project and install using setuptools:
python3 setup.py install
or install the package from PyPi:
pip3 install sdm_modbus
The script example.py provides a minimal example of connecting to and displaying all input and holding registers on a SDM120 over Modbus TCP. To display values as a JSON object, add --json.
usage: example.py [-h] [--unit UNIT] [--json] host port
positional arguments:
host Modbus TCP address
port Modbus TCP port
optional arguments:
-h, --help show this help message and exit
--unit UNIT Modbus device address
--json Output as JSON
Output:
SDM120(10.0.0.123:502, connectionType.TCP: timeout=1, retries=3, unit=0x1):
Input Registers:
Voltage: 237.00V
Current: 8.63A
Power (Active): -1919.70W
Power (Apparent): 2035.57VA
Power (Reactive): -676.70VA
Power Factor: -0.94
Phase Angle: 0.00°
Frequency: 50.00Hz
Imported Energy (Active): 1551.37kWh
Imported Energy (Active): 1335.69kWh
Imported Energy (Reactive): 0.01kVAh
Exported Energy (Reactive): 4362.14kVAh
Total Demand Power (Active): 1668.02W
Maximum Total Demand Power (Active): 3347.26W
Import Demand Power (Active): 0.00W
Maximum Import Demand Power (Active): 3347.26W
Export Demand Power (Active): 1668.02W
Maximum Export Demand Power (Active): 2109.45W
Total Demand Current: 7.57A
Maximum Total Demand Current: 14.97A
Total Energy (Active): 2887.07kWh
Total Energy (Reactive): 0.00kVAh
Holding Registers:
Demand Time: 1s
Demand Period: 60s
Relay Pulse Width: 60ms
Network Parity Stop: N-1
Meter ID: 1
Baud Rate: 9600
P1 Output Mode: Export Energy (Active)
Display Scroll Timing: 0s
P1 Divisor: 0.001kWh/imp
Measurement Mode: 0
Pulse/LED Indicator Mode: Import + Export Energy (Active)
If you wish to use Modbus TCP the following parameters are relevant:
host = IP or DNS name of your Modbus TCP gateway, required
port = TCP port of the Modbus TCP gateway, required
unit = Modbus device address, default=1, optional
While if you are using a Modbus RTU connection you can specify:
device = path to serial device, e.g. /dev/ttyUSB0, required
baud = baud rate of your SDM unit, defaults to factory default, optional
unit = Modbus device address, defaults to 1, optional
Connecting to the meter:
>>> import sdm_modbus
# SDM120 over Modbus TCP
>>> device = sdm_modbus.SDM120(host="10.0.0.123", port=502)
# SDM630 over Modbus RTU
>>> device = sdm_modbus.SDM630(device="/dev/ttyUSB0", baud=9600)
Test the connection:
>>> device.connected()
True
Printing the class yields basic device parameters:
>>> device
SDM120(10.0.0.123:502, connectionType.TCP: timeout=1, retries=3, unit=0x1):
Re-using an existing RTU or TCP connection is possible by providing an already connected device as parent when creating a new instance. This may be necessary if the Modbus TCP gateway only accepts a limited number of connections, or you wish to address multiple RTU devices on the same bus. For example:
# Connect to a SDM630 over Modbus TCP
>>> device_1 = sdm_modbus.SDM630(host="10.0.0.123", port=502, unit=1)
# Connect to a SDM630 using the existing connection
>>> device_2 = sdm_modbus.SDM630(parent=device_1, unit=2)
Reading a single input register by name:
>>> device.read("voltage")
236.89999389648438
Read all input registers by passing the sdm_modbus.registerType.INPUT enum to read_all(). Leave this blank to read both INPUT and HOLDING registers:
>>> device.read_all(sdm_modbus.registerType.INPUT)
{
"voltage": 238.60000610351562,
"current": 7.59499979019165,
"power_active": -1673.800048828125,
"power_apparent": 1797.5904541015625,
"power_reactive": -655.4000244140625,
"power_factor": -0.9311425685882568,
"phase_angle": 0.0,
"frequency": 50.0,
"import_energy_active": 1556.35595703125,
"export_energy_active": 1345.9210205078125,
"import_energy_reactive": 0.014999999664723873,
"export_energy_reactive": 4376.02001953125,
"total_demand_power_active": 1659.360107421875,
"maximum_total_demand_power_active": 3347.26318359375,
"import_demand_power_active": 0.0,
"maximum_import_demand_power_active": 3347.26318359375,
"export_demand_power_active": 1659.360107421875,
"maximum_export_demand_power_active": 2109.4541015625,
"total_demand_current": 7.531858921051025,
"maximum_total_demand_current": 14.968546867370605,
"total_energy_active": 2902.277099609375,
"total_energy_reactive": 4376.03515625
}
>>> device.read_all(sdm_modbus.registerType.HOLDING)
{
"demand_time": 1,
"demand_period": 60,
"relay_pulse_width": 60,
"network_parity_stop": 0,
"meter_id": 1,
"baud": 2,
"p1_output_mode": 4,
"display_scroll_timing": 0,
"p1_divisor": 0,
"measurement_mode": 0,
"indicator_mode": 0
}
Writing to holding registers is also possible. Setting a new baud rate, for example:
>>> device.write("baud", 2)
WriteMultipleRegisterResponse (28,2)
You will need to enable setup mode on your device by pressing the setup button for 5 seconds, otherwise you will receive a Exception Response(134, 6, GatewayNoResponse) or similar.
If you need more information about a particular register, to look up the units or enumerations, for example:
>>> device.registers["voltage"]
# address, length, type, datatype, valuetype, name, unit, batching
(
0,
2,
<registerType.INPUT: 1>,
<registerDataType.FLOAT32: 11>,
<class 'float'>,
'Voltage',
'V',
1
)
>>> device.registers["p1_divisor"]
# address, length, type, datatype, valuetype, name, unit, batching
(
63760,
2,
<registerType.HOLDING: 2>,
<registerDataType.FLOAT32: 11>,
<class 'int'>,
'P1 Divisor',
['0.001kWh/imp', '0.01kWh/imp', '0.1kWh/imp', '1kWh/imp'],
2
)
Contributions are more than welcome, especially testing on supported units, and adding other Eastron SDM units.