Some try-outs with Python and network adaptor low-level communiation

Goal

This project tries to use cheap powerline network adaptors for communication with electric cars charging system.

References

[i] https://www.goingelectric.de/wiki/CCS-Technische-Details/ [ii] https://openinverter.org/forum/viewtopic.php?p=37085#p37085

Quick start / overview

• Modify a PLC adaptor hardware, that it runs on battery
• Modify the configuration of the PLC adaptor, that it supports HomePlug Green Phy including the SLAC.
• Install wireshark to view the network traffic
• Install Pcap-ct python library
• Patch Pcap-ct to support non-blocking operation

Hardware preparation

Tested device: TPlink TL-PA1040P Ver 5.0

• remove the housing
• remove the AC power connector parts
• connect cables to supply the device by battery. Works with 12V, also works with 5V from an USB power bank.
• connect cables and circuit (1nF and 150ohms in series) for connecting to the pilot line.

Configuration of the PLC adaptor

The factory settings of the Homeplug PLC adaptor do not in all cases support the requirements of the communication with the car. In detail, the adaptors are supporting HomePlugAV, but we need HomePlugGP (Green Phy). This is similar, but not the same. Fortunately, the supplier of the chipset is aware of this topic, and provides some smart helper tools. http://github.com/qca/open-plc-utils It is worth to read its documentation, starting in docbook/index.html, this contains all what we need for the next steps.

(Tested on Linux/Raspbian on a raspberryPi 3)

Find the PLC adaptor pi@RPi3D:~ $ int6klist -ieth0 -v This shows the software version and the mac address.

Read the configuration from the PLC adaptor and write it to a file pi@RPi3D:~ $ plctool -ieth0 -p original.pib 98:48:27:5A:3C:E6 eth0 98:48:27:5A:3C:E6 Read Module from Memory

Patch the configuration file (aee /docbook/ch05s15.html). For each side (pev (vehicle) and evse (charger)) there is a special configuration. Example pev side: pi@RPi3D:~ $ cp original.pib pev.pib pi@RPi3D:~ $ setpib pev.pib 74 hfid "PEV" pi@RPi3D:~ $ setpib pev.pib F4 byte 1 pi@RPi3D:~ $ setpib pev.pib 1653 byte 1 pi@RPi3D:~ $ setpib pev.pib 1C98 long 10240 long 102400

Write the configuration file to the PLC adaptor pi@RPi3D:~ $ plctool -ieth0 -P pev.pib 98:48:27:5A:3C:E6 eth0 98:48:27:5A:3C:E6 Start Module Write Session eth0 98:48:27:5A:3C:E6 Flash pev.pib ... eth0 98:48:27:5A:3C:E6 Close Session eth0 98:48:27:5A:3C:E6 Reset Device eth0 98:48:27:5A:3C:E6 Resetting ...

The open-plc-utils contain the programs evse and pev, which can be used for try-out of the functionality, using two PLC adaptors.

Installation / Preconditions on PC side

Usage on Windows10

1. Install python (windows automatically launches the installer if you type „python“ into the search field of the task bar)
2. Wireshark is already installed, this includes the pcap driver, which is necessary for low-level-network-interaction

Attention: There are (at least) three different python-libs available for pcap:

• Libpcap
• Pylibpcap (But: only Python2)
• Pypcap (recommented on https://stackoverflow.com/questions/63941109/pcap-open-live-issue)
• Pcap-ct (https://pypi.org/project/pcap-ct/) We use the last one. python -m pip install --upgrade pcap-ct This is fighting against the Libpcap-installation, so we need to deinstall the second: python -m pip uninstall libpcap Then again install pcap-ct, and finally add in the libpcap_platform__init__py the missing is_osx = False. (Is in the meanwhile fixed in the github repository.)

Now, in the IDLE shall 3.10.6, the import works: import pcap sniffer = pcap.pcap(name=None, promisc=True, immediate=True, timeout_ms=50) addr = lambda pkt, offset: '.'.join(str(pkt[i]) for i in range(offset, offset + 4)) for ts, pkt in sniffer: print('%d\tSRC %-16s\tDST %-16s' % (ts, addr(pkt, sniffer.dloff + 12), addr(pkt, sniffer.dloff + 16)))

Usage on Raspberry

Pcap-ct does not work with Python 3.4. After update to Python 3.8, it works.

Further steps

(to be continued)