ocpp-sim

A simulated OCPP charge point (1.6J, OCPP-S 1.6, 2.0.1 and 2.1) for testing central systems without a charger; not affiliated with the Open Charge Alliance.

One ChargePoint connects to a central system in the version you choose, boots, reports its connectors, authorizes, runs sessions with meter values and answers the central system's commands. Every message it sends and receives is checked against the Open Charge Alliance's JSON schemas, and what does not pass is recorded (Violations), so a test notices a central system that drifts from them. It is built on ocpp. Written for SigmaM2M, a oneM2M platform, whose CSMS tests run against it; it has no dependency on it.

go get github.com/cB-Sigma/ocpp-sim@latest

Requires Go 1.26.0 or later. The command:

go install github.com/cB-Sigma/ocpp-sim/cmd/ocppsim@latest

ocppsim -url ws://127.0.0.1:8887/ocpp/ -id CP1 -version 2.1 -session
ocppsim -soap -url http://127.0.0.1:8887/ocpp16s/ -id CP1 -version 1.6

cp := sim.New(sim.Config{URL: "ws://127.0.0.1:8887/ocpp/", ID: "CP1", Version: ocpp.V201})
_ = cp.Connect(ctx)
defer cp.Disconnect()
status, _ := cp.Boot(ctx)                     // "Accepted"
tx, _, _ := cp.Start(ctx, 1, "TAG1", 1000)    // a session on EVSE 1
_ = cp.Meter(ctx, 1, 1500, 7400, [3]float64{230, 230, 230})
_ = cp.Stop(ctx, 1, 2000, "Local")
r, _ := cp.Wait(ctx, "RequestStartTransaction") // a command from the central system
for _, v := range cp.Violations() { t.Error(v) }  // messages outside the schemas

Example in example_test.go runs the simulator against a small central system built from the ocpp module alone.

Reference: https://pkg.go.dev/github.com/cB-Sigma/ocpp-sim

Changes per version are in CHANGELOG.md.

go test -race ./...
cd interop && go test -v ./...                          # ocpp-go and seanlee0923/ocpp, in process (Go 1.26.5)
cd interop && SIGMA_OCPP_INTEROP=1 go test -v ./...     # and mobilityhouse/ocpp, needs Docker

Tests carry // Covers: SIG-... comments: requirement IDs of the SigmaM2M project's compliance report, with no meaning outside it; the tests added for the first release carry none.

• mobilityhouse/ocpp 2.1.0's central system (2026-10-11, python:3.12.10-slim in Docker Desktop 29.4.3 on arm64; interop): for 1.6, 2.0.1 and 2.1 the simulator booted, sent a heartbeat, authorized, ran a session with meter values (StartTransaction, MeterValues, StopTransaction; TransactionEvent Started, Updated, Ended), all of which mobilityhouse's schema check accepted; it answered RemoteStartTransaction and RemoteStopTransaction (1.6) or RequestStartTransaction and RequestStopTransaction (2.x) and started and stopped the session asked for, then Reset, GetConfiguration with a key list (1.6) or SetVariables and GetVariables (2.x), each answer accepted by mobilityhouse's schema check. A StatusNotification with a string connector, sent on purpose, came back as TypeConstraintViolation and the connection carried on; a Reset outside the enumeration, sent by mobilityhouse past its own check, was recorded in Violations.
• lorenzodonini/ocpp-go v0.19.0's 1.6 central system and 2.0.1 CSMS (2026-10-11, in process; interop): the same session and commands, read by ocpp-go's handlers with the values sent; no message of ocpp-go's fell outside the OCA schemas. ocpp-go answers the deliberately invalid StatusNotification with FormationViolation (1.6) and FormatViolation (2.0.1). Its 2.0.1 CSMS sends RequestStopTransaction as soon as it has read a Started event, which found a simulator bug (below).
• Bugs found and fixed for v0.1.0: GetConfiguration with keys answered every key and no unknownKey (found while writing the mobilityhouse test; TestGetConfigurationAskedKeys); a 2.x station recorded its transaction only after the Started event was answered, so it refused a RequestStopTransaction that came at once (TestTransactionKnownWhenStartedIsSent).
• SigmaM2M's CSMS is tested against this simulator for every version, OCPP-S included, and runs the OCA part 6 CSMS test cases with it.
• seanlee0923/ocpp v0.3.0's 2.1 CSMS (2026-10-12, in process; interop): the simulator booted, reported both connectors, sent a heartbeat and a SEND (NotifyPeriodicEventStream, three values) that seanlee's typed SEND handler decoded, and answered its Reset; no message of seanlee's fell outside the OCA schemas. Passed.
• Not yet: OCPP-S against another central system (SteVe speaks it; not run yet), security profiles 2 and 3 against another implementation.

Every charger identity, id tag, certificate and key in this module is made up or generated when the tests run. Do not use them for real chargers.

• ocpp: the OCPP protocol core this simulator is built on.

v0.x: the API may change before v1.

See CONTRIBUTING.md.

See SECURITY.md.

Apache-2.0 (see LICENSE and NOTICE). Copyright 2026 Abhinav Gautam. OCPP and Open Charge Alliance are names of the Open Charge Alliance; they are used only to say which protocol this module simulates. This module is not made, endorsed, certified or supported by the Open Charge Alliance.