Practical guides for CSMS teams: OCPP simulator comparisons, testing strategies, and protocol deep dives.
OCPP 2.1 builds on 2.0.1 and adds tariffs, bidirectional charging, DER control, payment and battery swap. Here is what changed, what a SimItNow 2.1 station does with it, and what it leaves out.
Read article →Most SimItNow features simulate a station that dials out to your CSMS. The hosted CSMS reverses that: your charger or firmware dials in. Here is how the address, the two access modes and the activity log work.
Read article →A charger on a cellular link will drop off the network. What matters for your CSMS is what arrives afterwards: late transactions, placeholder ids, offline flags and a burst of queued meter values. Here is how to produce each one on demand.
Read article →A station can fail to connect at five different points, and they all look like 'it does not work'. SimItNow's probe runs one real handshake and tells you how far it got. Here is how to read the result and what to fix.
Read article →The API reference at /docs is written for a person reading a page. /openapi.json and /llms.txt are written for tools: an AI coding assistant, an API client generator, or Postman. Here is how to point each of them at SimItNow and get a working integration out the other end.
Read article →Autocharge is the de facto standard for RFID-free AC charging: the station reads the EV's MAC address over the same physical link ISO 15118 uses, formats it as an idTag, and lets the CSMS authorize the session automatically. Here is how the flow works end to end, and how to exercise every branch of it, including the unregistered vehicle that every real Autocharge integration eventually meets, without owning an Autocharge-capable car or charger.
Read article →SimItNow is a cloud service, so it dials out to whatever CSMS URL you give it. If your CSMS is running on localhost, SimItNow's servers can't reach it until you expose it with a public tunnel. Here is how to do that with ngrok or Cloudflare Tunnel.
Read article →A reservation restricts who may start a transaction on a connector, not whether a cable may be plugged in. That distinction is where reservation bugs tend to hide, and it is hard to test without a simulator that models it correctly.
Read article →A charging profile can be set once and forgotten, or pushed live in the middle of a session to react to a real-time signal. Both are the same OCPP command. The difference is entirely in how and when your CSMS sends it, and both need to be tested separately.
Read article →Happy-path tests tell you the system works. Invalid scenario tests tell you it won't break in production. This covers what to test, and how SimItNow makes each scenario reproducible.
Read article →AC chargers top out around 22 kW. DC fast chargers go from 50 kW to 350 kW. The difference matters for CSMS billing, smart charging profile limits, and how a simulator needs to behave.
Read article →A multi-connector charge point can run two or more sessions simultaneously. Testing that concurrency in your CSMS, including session isolation, per-connector meter tracking, and smart charging across connectors, requires a simulator that handles it correctly.
Read article →MeterValues is how a charging station reports energy delivery to the CSMS. Static dummy values hide a class of billing and SOC bugs that only surface when the simulator meters realistically.
Read article →Unit tests cannot catch OCPP protocol bugs, because you need a live charging station to connect. A REST-driven simulator makes OCPP integration tests viable in any CI pipeline.
Read article →A CSMS is the backend that every EV charger talks to over OCPP. It authorizes sessions, tracks energy, controls power limits, and manages hundreds of stations remotely. Here is how it works and how teams test it.
Read article →When a charging station has a hardware or software problem, it tells the CSMS via a StatusNotification error code. Your CSMS needs to handle each one correctly, and testing that requires fault injection.
Read article →Authorization in OCPP has multiple layers: online CSMS lookup, local authorization list, and authorization cache. The interactions between them, especially offline, are a common source of hard-to-reproduce bugs.
Read article →Smart charging lets a CSMS control how much power each charger draws. SetChargingProfile is the command that makes it work. Here is how the profile model works and how to test it.
Read article →OCPP is a persistent WebSocket protocol rather than a REST API. Understanding the connection URL, message format, and reconnect behaviour matters for CSMS developers and simulator users alike.
Read article →OCPP 1.6 is still the most widely deployed version, and OCPP 2.0.1 is where the industry is heading. CSMS developers supporting both need to understand the differences in device model, transaction messages, and security.
Read article →A technical comparison of OCPP simulator options for CSMS/CPMS teams: open-source tools versus managed SaaS, covering protocol support, deployment complexity, scale, and maintenance.
Read article →An OCPP simulator is software that speaks the OCPP protocol exactly like a real charging station, without any hardware. Here is what it does and why CSMS teams rely on one.
Read article →External coverage
Read the launch note for SimItNow's OCPP 2.0.1 simulator support, including TransactionEvent lifecycle, multi-EVSE scenarios, smart charging, device model behavior, and security handlers.
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