Modification of the EmonTCPModbusInterfacer to work with Pymodbus 1.4.0

[alexandrecuer]

Tested on a Modbus TCP master SOFREL S500

[TrystanLea]

Thanks @alexandrecuer, what do you think would be the best way to catch the case where pymodbus is not installed? I got the following error when testing your changes:

Traceback (most recent call last):
  File "src/emonhub.py", line 24, in <module>
    from interfacers import *
  File "/home/pi/emonhub/src/interfacers/EmonModbusTcpInterfacer.py", line 3, in <module>
    from pymodbus.constants import Endian
ImportError: No module named pymodbus.constants

If I move the imports to within init, this avoids the error on systems where an EmonModbusTcpInterfacer configuration is not present, but it might be better to do a bit more error catching than this.. any suggestions welcome

class EmonModbusTcpInterfacer(EmonHubInterfacer):

    def __init__(self, name, modbus_IP='192.168.1.10', modbus_port=0):
        """Initialize Interfacer
        com_port (string): path to COM port
        """

        from pymodbus.constants import Endian
        from pymodbus.payload import BinaryPayloadDecoder
        from pymodbus.client.sync import ModbusTcpClient as ModbusClient

[TrystanLea]

PS: thankyou for removing the lines:

if I['Type'] in ('EmonModbusTcpInterfacer','EmonFroniusModbusTcpInterfacer') and not pymodbus_found
    self._log.error("Python module pymodbus not installed. unable to load modbus interfacer")

I missed these and have been trying to remove all module specific code from emonhub.py

[beaylott]

We could test this with a Victron battery system and will be in a position to test this soon with a SolarEdge inverter. Let me know if needed.

[alexandrecuer]

@TrystanLea : Indeed I see.... sorry in the rush I forgot the case pymodbus was not present
Injection in the constructor as you propose is not working for me
I will try to find something working on both cases and come back to you

@beaylott : good if you can test - if you have pymodbus installed, it should work

[alexandrecuer]

@TrystanLea : I've amended my pull request so that it is not producing anymore any error when pymodbus is not present...

[glynhudson]

Thansks! @TrystanLea can this be merged now? Sorry for the delay.

[alexandrecuer]

@TrystanLea @glynhudson @pb66
I recoded the whole interfacer on order to simplify the configuration in emonhub.conf
cf the following issue opened by pb66 in dec 2017 :
#43

Configuration in emonhub.conf is realised as follow :

Sample interfacer config within emonhub.conf

 [[ModbusTCP]]     
        # this interfacer retrieves register information from modbusTCP clients 
        # retrieve register information from modbus TCP documentation for your inverter.
        Type = EmonModbusTcpInterfacer
        [[[init_settings]]]
            modbus_IP = 192.168.1.10   # ip address of client to retrieve data from
            modbus_port = 502          # Portclient listens on
        [[[runtimesettings]]]
            # List of starting registers for items listed above
            register = 40118,40092,40102,502,40285,40305,40284,40304,40086,40088,40090
            # nodeid used to match with node definition in nodes section below. Can be set to any integer value not previously used.
            nodeId = 12
            # Channel to publish data to should leave as ToEmonCMS
            pubchannels = ToEmonCMS,
            # time in seconds between checks, This is in addition to emonhub_interfacer.run() sleep time of .01
            # use this value to set the frequency of data retrieval from modbus client
            interval = 10 

Sample Node declaration

    [[12]]
        nodename = fronius
        [[[rx]]]
            # list of names of items being retrieved
            # This example retrieves the Inverter status, AC power in watts being produced, AC Lifetime KWh produced,
            # KWh produced for current day,....
            names = Inverter_status,AC_power_watts,AC_LifetimekWh,DayWh,mppt1,mppt2,Vmppt1,Vmppt2,PhVphA,PhVphB,PhVphC
            datacodes = H,f,f,Q,H,H,H,H,f,f,f
            scales = 1,0.1,0.1,1,1,1,1,1,0.1,0.1,0.1
            units = V,W,kWh,Wh,W,W,V,V,V,V,V

hope all that is compatible with emonhub policy of code....

regards
Alex

[glynhudson]

Thanks, very sorry too so long to merge 👍