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ISO 15118 is the international standard for Vehicle-to-Grid (V2G) communication. EVerest provides comprehensive support for ISO 15118-2, ISO 15118-20, and DIN SPEC 70121 through specialized modules that enable advanced features like Plug & Charge, bidirectional charging, and optimized energy management.
ISO 15118 modules are located in modules/EVSE/ and include EvseV2G, EvseSlac, EvseSecurity, and related components.

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ISO 15118 Protocol Stack

The complete ISO 15118 implementation requires several cooperating modules:

EvseV2G

ISO 15118-2 and DIN 70121 application layer

EvseSlac

SLAC data link layer (PLC communication)

EvseSecurity

Certificate and key management

EvseManager

Coordination and charging state machine

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EvseV2G Module

The EvseV2G module implements the ISO 15118-2 and DIN SPEC 70121 protocols for high-level communication with electric vehicles.

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Supported Protocols

  • ISO 15118-2: International standard for AC and DC charging
  • DIN SPEC 70121: German predecessor to ISO 15118-2 (DC charging)
  • Plug & Charge (PnC): Certificate-based authentication
  • TLS Security: Encrypted communication with contract certificates

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EvseV2G Configuration

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device
string
default:"eth0"
Ethernet device used for HLC. Any interface with IPv6 link-local and MAC address.
This is the network interface for ISO 15118 communication, not the SLAC interface.
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supported_DIN70121
boolean
default:"true"
Enable support for DIN SPEC 70121 protocol
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supported_ISO15118_2
boolean
default:"true"
Enable support for ISO 15118-2 protocol
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tls_security
string
default:"allow"
Controls encrypted communication:
  • prohibit: No TLS, only basic communication
  • allow: TLS optional, fallback to basic
  • force: Require TLS, reject unencrypted sessions
Use force for production Plug & Charge implementations.
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verify_contract_cert_chain
boolean
default:"false"
Enable local verification of contract certificate chain
When enabled, the EVSE verifies the EV’s contract certificate against the V2G root certificates.
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auth_timeout_pnc
integer
default:"55"
Timeout in seconds for PnC authorization. Set to 0 to wait indefinitely.
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auth_timeout_eim
integer
default:"300"
Timeout in seconds for EIM authorization. Set to 0 to wait indefinitely.
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terminate_connection_on_failed_response
boolean
default:"false"
  • true: Terminate V2G connection immediately on failed response
  • false: Let EV close session with SessionStop
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enable_sdp_server
boolean
default:"true"
Enable the built-in SECC Discovery Protocol (SDP) server
Required for EVs to discover the charging station over IPv6.

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TLS and Certificate Configuration

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tls_key_logging
boolean
default:"false"
Enable export of TLS session keys for debugging
For testing and simulation ONLY. Never enable in production.
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tls_key_logging_path
string
default:"/tmp"
Output directory for TLS key log files (for Wireshark decryption)
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tls_timeout
integer
default:"15000"
TLS handshake timeout in milliseconds

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EvseV2G Interfaces

charger (ISO15118_charger)

Main interface implementing ISO 15118-2 for AC or DC chargerProvides:
  • Session management
  • Charging parameter negotiation
  • Certificate handling
  • Payment options (EIM/PnC)
Data sharing between ISO 15118 and OCPP modules for protocol interoperability
Required: Certificate and key management
  • V2G root certificates
  • Leaf certificates for SECC
  • Contract certificate validation

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EvseSlac Module

The EvseSlac module implements the SLAC (Signal Level Attenuation Characterization) protocol for establishing HomePlug Green PHY communication over the charging cable.

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SLAC Protocol Overview

SLAC is defined in ISO 15118-3 and enables:
  • PLC (Power Line Communication) link establishment
  • Unique logical network per charging session
  • Prevention of cross-talk between vehicles
  • Network Membership Key (NMK) exchange

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EvseSlac Configuration

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device
string
default:"eth1"
Ethernet device used for PLC communication
This must be the interface connected to your PLC modem (e.g., QCA7000, QCA7005, CG5317).
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number_of_sounds
integer
default:"10"
Number of sounding signals for attenuation measurement
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ac_mode_five_percent
boolean
default:"true"
Use AC 5% mode per ISO 15118-3 with retry on failure
Set to true even for DC charging. Many EVs fail SLAC without this option.
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set_key_timeout_ms
integer
default:"1000"
Timeout for CM_SET_KEY.REQ message. Default works for QCA7000/QCA7005/CG5317.
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publish_mac_on_match_cnf
boolean
default:"true"
Publish EV MAC address when matching is confirmed
Can be used for AC Autocharge as alternative to EVCCID from HLC.

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Advanced SLAC Configuration

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do_chip_reset
boolean
default:"false"
Perform chip reset after setting NMK using RS_DEV.REQ vendor MME
Only works on Qualcomm chips. May improve stability.
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link_status_detection
boolean
default:"false"
Wait for link to come up before signaling d_link_ready
Works on Qualcomm and Lumissil chips. Ensures PLC link is stable before proceeding.
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link_status_timeout_ms
integer
default:"10000"
Timeout for link to establish after matching
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slac_init_timeout_ms
integer
default:"40000"
Timeout for CM_SLAC_PARM.REQ. Range: 10000-50000ms
Values below 20000ms violate ISO 15118-3 but may work in practice.
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reset_instead_of_fail
boolean
default:"true"
Go to reset state instead of failed state on SLAC abort
Violates ISO 15118-3 but allows recovery when EVs send CM_SLAC_PARAM.req after abort.

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ISO 15118 Configuration Example

active_modules:
  # ISO 15118-2 Application Layer
  iso15118_charger:
    module: EvseV2G
    config:
      device: eth0
      supported_DIN70121: true
      supported_ISO15118_2: true
      tls_security: allow
      verify_contract_cert_chain: false
      auth_timeout_pnc: 55
      auth_timeout_eim: 300
      enable_sdp_server: true
    connections:
      security: evse_security
      
  # SLAC Data Link Layer  
  slac:
    module: EvseSlac
    config:
      device: eth1
      number_of_sounds: 10
      ac_mode_five_percent: true
      publish_mac_on_match_cnf: true
      link_status_detection: false
      slac_init_timeout_ms: 40000
      
  # Security and Certificates
  evse_security:
    module: EvseSecurity
    config:
      csms_leaf_cert_directory: /certs/client/csms
      csms_leaf_key_directory: /certs/client/csms  
      secc_leaf_cert_directory: /certs/client/secc
      secc_leaf_key_directory: /certs/client/secc
      v2g_root_cert_directory: /certs/ca/v2g
      
  # EVSE Manager Integration
  evse_manager:
    module: EvseManager
    config:
      ac_hlc_enabled: true
      ac_hlc_use_5percent: true
      payment_enable_contract: true
    connections:
      hlc: iso15118_charger
      slac: slac

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Plug & Charge Flow

The complete Plug & Charge sequence:
1

Vehicle Plug-in

EV is connected to charging station
2

SLAC Matching

EvseSlac establishes PLC communication and exchanges NMK
3

SDP Discovery

EV discovers SECC via SDP server (IPv6 multicast)
4

TCP/TLS Connection

ISO 15118 session established with optional TLS
5

Authorization

EV presents contract certificate, EVSE validates
6

Charging Parameters

Negotiate voltage, current, energy, schedules
7

Energy Transfer

Charging begins based on negotiated parameters
8

Session End

SessionStop request and graceful disconnect

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Certificate Management

Plug & Charge requires proper certificate hierarchy: 
V2G Root CA
├── CPO Sub-CA 1
│   └── SECC Leaf Certificate (charging station)
└── CPO Sub-CA 2
    └── Contract Certificate Root
        └── OEM Sub-CA
            └── Contract Certificate (in vehicle)

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Certificate Directories

EvseSecurity module manages certificates:
  • V2G Root Certificates: Trusted roots for contract validation
  • SECC Leaf Certificates: Charging station identity
  • CSMS Leaf Certificates: Backend communication (OCPP)
  • Contract Certificates: Vehicle authorization
Refer to the EvseSecurity module documentation for certificate installation and management.

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ISO 15118-20 Support

EVerest has ISO 15118-20 support in development for:
  • Wireless Power Transfer (WPT)
  • Bidirectional Power Transfer (BPT)
  • Automatic Connection Device (ACD)
  • Enhanced scheduling
ISO 15118-20 modules are under active development. Check the EVerest repository for latest status.

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Debugging ISO 15118

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Enable Session Logging

evse_manager:
  config:
    session_logging: true
    session_logging_path: /var/log/everest/sessions
    session_logging_xml: true
This logs complete XML message exchanges for debugging.

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TLS Decryption

For development debugging: 
iso15118_charger:
  config:
    tls_key_logging: true
    tls_key_logging_path: /tmp/tls_keys
Use the key log file with Wireshark to decrypt TLS traffic.

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SLAC Debugging

slac:
  config:
    debug_simulate_failed_matching: false  # Set to true to test failure handling

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Common Issues

  • Verify correct PLC interface in device config
  • Check PLC modem is properly connected to CP/PP lines
  • Ensure ac_mode_five_percent: true for retry support
  • Increase slac_init_timeout_ms for slow EVs
  • Verify no electrical cross-talk between charging points
  • Verify SECC leaf certificate is installed
  • Check certificate validity period
  • Ensure V2G root certificates include EV’s contract issuer
  • Review TLS timeout settings
  • Enable TLS key logging to inspect handshake
  • Verify contract certificate validation is working
  • Check auth_timeout_pnc is sufficient
  • Ensure OCPP/Auth module receives authorization request
  • Review certificate chain completeness
  • Verify enable_sdp_server: true
  • Check IPv6 link-local address on HLC interface
  • Ensure SDP multicast routing is working
  • Verify firewall allows UDP port 15118

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Hardware Requirements

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PLC Modem

Supported chipsets:
  • Qualcomm QCA7000 - HomePlug Green PHY
  • Qualcomm QCA7005 - Integrated solution
  • Lumissil CG5317 - Alternative PLC modem

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Network Interface

Requires:
  • SPI or UART connection to PLC modem
  • Linux network interface (eth0, eth1, etc.)
  • IPv6 support for ISO 15118 communication

EvseManager

Charging coordination and HLC integration

OCPP

Backend integration for PnC

Authentication

Authorization handling

Hardware Drivers

PLC modem drivers

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Additional Resources

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Source Code Reference

  • modules/EVSE/EvseV2G/manifest.yaml - ISO 15118-2 configuration
  • modules/EVSE/EvseSlac/manifest.yaml - SLAC configuration
  • modules/EVSE/EvseSecurity/ - Certificate management
  • modules/EVSE/Iso15118InternetVas/ - VAS (Value Added Services)

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