ISO 15118-20

ISO 15118-20 is the second-generation high-level communication protocol for CCS. ChargeLink plays either role: the charger (SECC) for a vehicle or EVCC, or the vehicle (EVCC) for your charger or SECC. It speaks IPv6 link-local SDP, TCP, mutual TLS 1.3, V2GTP and EXI, and runs DC EIM (the full session of 16 request/response pairs from SupportedAppProtocol to SessionStop) and AC EIM (Scheduled and Dynamic control mode). As charger, ChargeLink runs plant-coupled on the NI VeriStand bench: every response is computed from the session state and the simulated power stage of the bench. As vehicle, ChargeLink runs the DC session with evcc activate-profile and the AC session with iso20-ac-evcc.

Before you start

• TLS 1.3 with mutual authentication is mandatory. ChargeLink rejects plaintext, TLS 1.2 and connections without a verified client certificate before the SupportedAppProtocol exchange. It negotiates only the named groups secp521r1 and x448 and the cipher suites TLS_AES_256_GCM_SHA384 and TLS_CHACHA20_POLY1305_SHA256.
• Production and engineering material. Production material follows ISO 15118-20 Annex B (ECDSA P-521, SHA-512). evse tls-material-init generates a fresh Annex B-shaped engineering chain on every run; evse start accepts it as the charger identity only with --allow-engineering-tls-identity.
• Legacy named groups. A peer that offers only other groups (for example P-256 or X25519) is refused before any V2G message. --allow-legacy-tls-named-groups adds secp256r1 after the standard groups; it is an engineering option outside ISO 15118-20, and the charger side then also needs --allow-engineering-tls-identity.
• The charger identity is validated as an Annex B chain to the V2G root. The DNS name is SNI only; the vehicle-side default --tls-server-name chargelink-secc.local does not need to match a SAN.

Every example on this page uses this block. The kit has a charger\ and a vehicle\ folder; chargelink.exe is the same binary in both.

$CL   = 'C:\Program Files\DEVlink\ChargeLink\<VERSION>\charger\bin\chargelink.exe'
$Data = "$env:ProgramData\DEVlink\ChargeLink\data"
$IfIndex   = <INTERFACE_INDEX>
$Advertise = 'fe80::<ADDRESS>%' + $IfIndex
$Pki       = "$Data\pki"

ChargeLink as charger

The ISO 15118-20 charger runs plant-coupled on the NI VeriStand bench, with profile iso15118_20_dc (DC EIM) or iso15118_20_ac_eim (AC EIM, below). The plant values (voltage, current, contactor, isolation) come from the VeriStand model, and PreCharge, PowerDelivery and the DC charge loop follow the vehicle's targets and the simulated electrical behaviour. The charger is delivered and verified with the ChargeLink vehicle on the VeriStand bench. Contact DEVlink before connecting a third-party vehicle.

The plant-coupled charger session (DC EIM)

On the NI VeriStand bench, the VeriStand operator starts this session for you with the package's runtime profile (ChargeLink Operator (VeriStand), see NI VeriStand Bench); you do not type the command. For reference, the session it starts has this shape:

chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json evse start --external-evcc-session --run-id $Run `
  --protocol iso15118-20 --profile-id iso15118_20_dc --exi-mode chargelink-exi `
  --plant-grpc-endpoint <BENCH_PLANT_ENDPOINT> --requested-power-kw <kW> --target-voltage-v <V> `
  [--evse-rated-current-a <A>] [--evse-rated-voltage-v <V>] `
  --host '::' --tcp-port 50118 --udp-port 15118 --advertise-ipv6 $Advertise --interface-index $IfIndex `
  --tls --tls-cert "$Pki\secc-chain.pem" --tls-key "$Pki\secc-key.pem" --tls-cafile "$Pki\v2g-root-ca.pem" --require-ca

• --plant-grpc-endpoint is the plant endpoint of the bench; there is no other plant option.
• --requested-power-kw and --target-voltage-v must be given explicitly (zero means unset and is rejected).
• The environment variable CHARGELINK_ISO20_RUNTIME_PROFILE points to the runtime profile JSON. The runtime profile sets the control modes offered (Scheduled, Dynamic, or both for the vehicle to choose); the package's runtime profile offers Scheduled. Its fields are described on the NI VeriStand Bench page.
• --tcp-port 0 picks a free port from 49152–65535; the bound port is reported in the JSON result and in evse_listener_status.json.
• Do not use --external-evcc-windows-tls or --external-evcc-dev-tls for ISO 15118-20: both select TLS 1.2, which the ISO 15118-20 admission check rejects.
• ChargeLink enforces its response budget: ChargeLoop 250 ms, ServiceDetail 4500 ms, CableCheck 38 s, other messages 1500 ms. A budget overrun is recorded as a finding.

Watch the session from a second window:

chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json evse status --run-id $Run
chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json evse list-state --run-id $Run

Network, SDP and TLS check without the bench

evse start without --plant-grpc-endpoint starts a reference responder with fixed reference responses and no plant. It is not a charging session: a vehicle stops early, at AuthorizationSetup. Use it only to check the network, SDP discovery and the TLS 1.3 handshake with the other side.

$Run = "iso20-check-$(Get-Date -Format yyyyMMdd-HHmmss)"

chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json evse live-preflight --source external-evcc `
  --protocol iso15118-20 --profile-id iso15118_20_dc `
  --host '::' --tcp-port 50118 --udp-port 15118 `
  --advertise-ipv6 $Advertise --interface-index $IfIndex `
  --tls --tls-cert "$Pki\secc-chain.pem" --tls-key "$Pki\secc-key.pem" --tls-cafile "$Pki\v2g-root-ca.pem" --require-ca `
  --recover-stale

chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json evse start --external-evcc-session --run-id $Run `
  --protocol iso15118-20 --profile-id iso15118_20_dc `
  --host '::' --tcp-port 50118 --udp-port 15118 `
  --advertise-ipv6 $Advertise --interface-index $IfIndex `
  --tls --tls-cert "$Pki\secc-chain.pem" --tls-key "$Pki\secc-key.pem" --tls-cafile "$Pki\v2g-root-ca.pem" --require-ca `
  --max-runtime-ms 1800000 --heartbeat-interval-ms 1000

--external-evcc-session keeps the listener open until --max-runtime-ms elapses or you stop it, and defaults UDP to 15118. The check is good when sdp_diagnostics.json records the SDP exchange and tls_handshake_diagnostics.json a completed TLS 1.3 handshake with the other side's certificate.

This check applies to the DC profile. The AC charger has no check without a plant (see below).

The plant-coupled charger session (AC EIM)

The AC charger runs plant-coupled only, with profile iso15118_20_ac_eim. It needs a plant behind --plant-grpc-endpoint: on the NI VeriStand bench, the bench's plant endpoint. Started without the endpoint, it refuses to start with "protocol-only AC is not offered". The session runs over mutual TLS 1.3 only, as ISO 15118-20 requires; the vehicle must present a certificate chain to the same V2G root. SDP runs on UDP 15118.

$env:CHARGELINK_ISO20_AC_RUNTIME_PROFILE = "$Data\profiles\iso20-ac-charger.json"
Remove-Item Env:\CHARGELINK_ISO20_RUNTIME_PROFILE -ErrorAction SilentlyContinue

chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json evse start --external-evcc-session --run-id $Run `
  --protocol iso15118-20 --profile-id iso15118_20_ac_eim --exi-mode chargelink-exi `
  --plant-grpc-endpoint <BENCH_PLANT_ENDPOINT> --requested-power-kw 11 --target-voltage-v 230 `
  --host '::' --tcp-port 50118 --udp-port 15118 --advertise-ipv6 $Advertise --interface-index $IfIndex `
  --tls --tls-cert "$Pki\secc-chain.pem" --tls-key "$Pki\secc-key.pem" --tls-cafile "$Pki\v2g-root-ca.pem" --require-ca

• --requested-power-kw and --target-voltage-v are required with --plant-grpc-endpoint (zero means unset and is rejected); give the outlet's power and nominal voltage. The AC limits themselves come from the settings file.
• The environment variable CHARGELINK_ISO20_AC_RUNTIME_PROFILE names the charger's AC settings file. The profile ID and the settings file belong together: either one alone is refused. Do not set the DC variable CHARGELINK_ISO20_RUNTIME_PROFILE in the same window.
• The kit contains no AC settings file. Write your own, as described below.
• With engineering TLS material from evse tls-material-init, add --allow-engineering-tls-identity.

The AC settings file

The settings file is JSON. A field the charger does not know is refused.

The dynamic block:

Example: a three-phase 11 kW charger that offers both control modes.

{
  "evse_id": "<EVSE_ID>",
  "parameter_set_id": 1,
  "connector": 2,
  "nominal_voltage_v": 230,
  "nominal_frequency_hz": 50,
  "evse_max_current_per_phase_a": 16,
  "cable_rating_a": 32,
  "evse_minimum_charge_power_w": 1380,
  "schedule_tuple_id": 1,
  "schedule_duration_s": 3600,
  "meter_id": "<METER_ID>",
  "free_service": true,
  "terminate_notification_max_delay_s": 10,
  "dynamic": {
    "offer_scheduled": true,
    "policy_mode": "max_available",
    "available_power_steps": [ { "after_ms": 0, "power_w": 11000 }, { "after_ms": 60000, "power_w": 7000 } ]
  }
}

Control modes: the charger always offers Scheduled when dynamic is absent; with dynamic it offers Dynamic only, or both when offer_scheduled is true. In both modes the vehicle states its mobility needs (MobilityNeedsMode 1). The charger answers a power tolerance the vehicle confirms with OK_PowerToleranceConfirmed; it offers no tolerance itself.

What a good AC charger session looks like: protocol\iso20_ac_secc_session_evidence.json in the run folder reads "result": "session_stop" and "profile_id": "iso15118_20_ac_eim"; iso20_ac_frames.jsonl beside it has one row per frame, with the response code and response time of each response. evse_listener_status.json reads "status": "stopped" after evse stop.

The DC EIM session at a glance

What a good session looks like

The run folder is <artifact-root>\<run-id>\. After evse stop:

• evse_listener_status.json reads "status": "stopped".
• command_result.json reads "status": "stopped".
• evse_message_trace.jsonl shows the request/response pairs in order, from SupportedAppProtocol to SessionStop; events.jsonl, diagnostics.json and conformance_traceability.json complete the evidence.
• The process exits with code 0. The exit code alone is not the verdict: read the status fields.

ChargeLink as vehicle

Your DUT is a charger or SECC. Connect it to the ChargeLink PC's adapter. For DC EIM, the vehicle runs evcc activate-profile with profile iso15118_20_dc_evcc_reference (steps 1 and 2 below). For AC EIM, it runs the iso20-ac-evcc command, which takes no profile (step 3). Contact DEVlink before connecting the DC vehicle to a third-party charger.

Your charger must:

• offer SDP on the link (or accept a direct TCP connection, see below);
• offer TLS 1.3 with an ISO 15118-20 Annex B chain on secp521r1 or x448. A P-256 chain is refused unless you add --allow-legacy-tls-named-groups, an engineering option outside ISO 15118-20;
• chain to the V2G root you pass with --tls-cafile. --tls-server-name sets the expected server name (default chargelink-secc.local).

1. Probe the charger (transport and TLS only)

Prove TCP reachability and the mutual TLS 1.3 handshake first. The probe deliberately takes no session arguments:

chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json evcc tls-handshake-probe `
  --protocol iso15118-20 --profile-id iso15118_20_dc_evcc_reference `
  --peer-ipv6 ('fe80::<SECC_ADDRESS>%' + $IfIndex) --tcp-port 50118 `
  --tls --tls-cert "$Pki\vehicle-chain.pem" --tls-key "$Pki\vehicle-key.pem" --tls-cafile "$Pki\v2g-root-ca.pem" --require-ca

Judge the result on the reported status, not on the exit code: the exit code says whether the probe ran, the status says what the charger decided. The link-local zone index must be the ChargeLink PC's interface index, not the charger's.

2. Run the DC EIM session

The vehicle session refuses to run with hidden defaults. Name two files from the vehicle folder of the kit (vehicle\cases) in environment variables before you start evcc activate-profile. The EV values in them are test values, not a vehicle implementation.

$env:CHARGELINK_ISO20_LIVE_SEMANTIC_CASE        = 'C:\Program Files\DEVlink\ChargeLink\<VERSION>\vehicle\cases\nominal.json'
$env:CHARGELINK_ISO20_FULL_WIRE_SESSION_MANIFEST = 'C:\Program Files\DEVlink\ChargeLink\<VERSION>\vehicle\cases\full-wire-session-manifest.json'

# standard flow: SDP discovery on the adapter to the charger
chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json evcc activate-profile `
  --protocol iso15118-20 --profile-id iso15118_20_dc_evcc_reference `
  --use-sdp --interface-index $IfIndex --tcp-port <CHARGER_TLS_PORT> --exi-mode chargelink-exi `
  --tls --tls-cert "$Pki\vehicle-chain.pem" --tls-key "$Pki\vehicle-key.pem" --tls-cafile "<V2G_ROOT_OF_THE_CHARGER_CHAIN>" --require-ca `
  --max-steps 14 --requested-power-kw 80

# to isolate transport problems: direct TCP (no --use-sdp, explicit peer and port)
chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json evcc activate-profile `
  --protocol iso15118-20 --profile-id iso15118_20_dc_evcc_reference `
  --peer-ipv6 ('fe80::<SECC_ADDRESS>%' + $IfIndex) --tcp-port <CHARGER_TLS_PORT> --probe-peer --exi-mode chargelink-exi `
  --tls --tls-cert "$Pki\vehicle-chain.pem" --tls-key "$Pki\vehicle-key.pem" --tls-cafile "<V2G_ROOT_OF_THE_CHARGER_CHAIN>" --require-ca `
  --max-steps 14 --requested-power-kw 80

--interface-index is the ChargeLink PC's interface to the charger. Every response wait is bounded by the ISO 15118-20 V2G_EVCC_Msg_Timeout for that message type. The vehicle stays inside the schedule it negotiated with the charger.

What a good session looks like

The run folder is <artifact-root>\cl-evcc-<id>\ (the JSON result names it):

• summary.json reads "status": "passed" and "session_stopped": true, and observed_state_count equals required_state_count (16 of 16 for a nominal DC session).
• command_result.json reads "status": "stopped".
• protocol_summary.json, protocol_session.json, the traces (evcc_message_trace.jsonl and .log, frames.jsonl, trace.jsonl), events.jsonl, diagnostics.json, manifest.json and conformance_traceability.json complete the evidence.
• The process exits with code 0. The exit code alone is not the verdict: read the status fields.

3. Run the AC EIM session

iso20-ac-evcc runs one ISO 15118-20 AC EIM session against your charger: SDP, mutual TLS 1.3 with the vehicle certificate chain, then one V2G communication session. It selects the AC service (ServiceID 1) and the offered parameter set whose control mode matches its own and whose mobility needs mode is 1. If the charger offers no matching set, the vehicle stops at once with SessionStopReq (Terminate).

# standard flow: SDP discovery
chargelink iso20-ac-evcc --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json `
  --sdp-server ('[fe80::<SECC_ADDRESS>%' + $IfIndex + ']:15118') `
  --tls-cert "$Pki\vehicle-chain.pem" --tls-key "$Pki\vehicle-key.pem" --tls-root "<V2G_ROOT_OF_THE_CHARGER_CHAIN>" `
  --phases 3 --ev-max-power-w 11000 --ev-min-power-w 1400 --charge-loops 20

# without SDP: the charger's TLS port
chargelink iso20-ac-evcc --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json `
  --peer ('[fe80::<SECC_ADDRESS>%' + $IfIndex + ']:50118') `
  --tls-cert "$Pki\vehicle-chain.pem" --tls-key "$Pki\vehicle-key.pem" --tls-root "<V2G_ROOT_OF_THE_CHARGER_CHAIN>"

The kit contains no AC vehicle case files. Describe the vehicle with the options below, or with --case <FILE>, a JSON case file with the EV settings it names over the defaults (a field the vehicle does not know is refused; with --case, the EV options below are not used). The Dynamic control mode is selected in a case file, with "control_mode": "dynamic"; without it the vehicle uses the Scheduled control mode.

The vehicle confirms the power tolerance of the schedule it selected in every PowerDeliveryReq. Per-phase values that the charger sends without the vehicle having asked for them are ignored and recorded; the vehicle goes on with the base values.

What a good AC session looks like

• The run folder is <artifact-root>\<run-id>\; without --run-id it is named iso20-ac-evcc-<number>, which the JSON result names.
• iso20_ac_evcc_report.json reads "passed": true. The command fails unless the session ended with SessionStopRes (or with your charger's FAILED answer to the fault the run asked for).
• traces\live-v2gtp-frames.jsonl holds one row per frame.

Results and evidence

Each run writes one folder under the artifact root: $Data\artifacts\<run-id>. Charger runs use the --run-id you pass; vehicle runs without one get a generated ID (cl-evcc-<id> for DC, iso20-ac-evcc-<number> for AC) that the JSON result names. For AC, the charger's session record is protocol\iso20_ac_secc_session_evidence.json with the frame list iso20_ac_frames.jsonl, and the vehicle's verdict is iso20_ac_evcc_report.json. Stop the charger, then check the evidence:

chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json evse stop --run-id $Run
chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json artifacts inspect --run-id $Run
chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json artifacts integrity --run-id $Run
chargelink --runtime-root "$Data\runtime" --artifact-root "$Data\artifacts" --json evse live-closure-gate --run-id $Run --source external-evcc `
  --require-sdp --require-tcp-peer --require-tls --require-v2gtp --require-exi --write-artifacts

evse live-closure-gate reads the charger's run folder and reports whether SDP, a live TCP peer, TLS, V2GTP exchange and EXI decoding were observed. artifacts integrity confirms that no file changed after the run. Every artifact carries a claim boundary: it is engineering evidence, not certification. See Trace, Evidence and Reports.

Limits

• EIM only. ChargeLink does not provide bidirectional power transfer (BPT) or Plug & Charge (Contract authorization): evse start refuses a profile whose ID names either (for example bpt, bidirectional, v2g, pnc, contract or plug) with exit code 70 (CL-UNSUPPORTED-001) before any socket opens.
• The TLS handshake accepts only the named groups secp521r1 and x448, unless --allow-legacy-tls-named-groups is given.
• The charging session of the charger role runs plant-coupled on the NI VeriStand bench; there is no other plant option. The charger is delivered and verified with the ChargeLink vehicle on the VeriStand bench. In DEVlink's own tests, ChargeLink's charger has also completed ISO 15118-20 DC sessions over Ethernet with a third-party vehicle stack; this has not been verified on the VeriStand bench. Connecting a real vehicle needs a physical layer (control pilot, PLC) that this release does not include. Contact DEVlink before connecting a third-party vehicle.
• Without --plant-grpc-endpoint, the DC charger is a reference responder with fixed responses and no plant. It is not a charging session; use it only to check the network, SDP and TLS. The AC charger does not start without a plant.
• AC: one charger that offers AC and DC together is not available; the AC charger runs under iso15118_20_ac_eim with its AC settings file, the DC charger under iso15118_20_dc.
• AC: the Dynamic control mode has been shown with the charger and the vehicle on one PC. On the NI VeriStand bench with the vehicle on a second PC, use the Scheduled control mode.
• AC: mobility needs mode 1 only (the vehicle states its needs). A charger that offers only mode 2 is stopped by the ChargeLink vehicle (Terminate) after ServiceDetailRes.
• AC: not offered are charger-initiated pause, service renegotiation, standby and pricing. The AC charger offers no power tolerance in its schedules; it answers a missing or unconfirmed tolerance with OK and records it.
• AC: a V2GTP frame with a wrong header ends the AC session on both sides instead of being ignored while the message timer runs; a wrong payload length also ends the session on a decode or timer error. Not safety-relevant.
• AC: faults inside the charger, such as a residual-current trip that opens the contactor, end the session through the charger's stop path, or the charger answers FAILED and contains the session; this behaviour is shown by DEVlink's own tests. The schema validity of each AC message is not checked during a run; it is covered by the AC codec's test vectors.
• Dynamic control mode supports MobilityNeedsMode 1 and pricing 0 only, with available power from a profile script. The charger never pauses or enters standby on its own.
• The package's runtime profile offers one 60 s charging schedule. Schedule renegotiation is answered when the vehicle requests it; the charger never triggers it. A longer session needs a vehicle that renegotiates or a runtime profile with a longer schedule.
• The charger does not handle CertificateInstallation or MeteringConfirmation.
• As vehicle, ChargeLink runs a live DC session with the profile iso15118_20_dc_evcc_reference and the EV case files of the kit; contact DEVlink before connecting the DC vehicle to a third-party charger. The live AC session runs with iso20-ac-evcc; the kit ships no AC vehicle case files, so you describe the vehicle with the command's options or your own case file.
• No physical charging interface (PLC, control pilot, power stage) is included.

See Capability Boundaries for every standard. To check the installation without a DUT, see Self-test without a device under test.

Troubleshooting

General failures (licence, ports, firewall, role locks) are in Troubleshooting.