Site Simulator — OCPP in this tab · Modbus gateways on the server
Add a gateway
A gateway connects to the cloud first (MQTT / Waveshare). Modbus devices are attached behind it. OCPP wallboxes live on the other tab and link here for site load only.
Cloud publishes Modbus RTU here (Waveshare module subscribes)
Cloud subscribes here for RS485 replies (module publishes)
Local: mqtt://localhost:1883 (monorepo python-mqtt). Cloud TLS: host mqtt.ems-dev… + port 8883 → auto mqtts:// (self-signed OK in this sim). Copy Sub/Pub from EMS wizard when targeting cloud. LWT on {base}/lwt with birth 0x01 / will 0x00.
Charge points are added on the OCPP tab.
OCPP 1.6 Charge Point
The charge point WebSocket runs in this browser tab (closing or removing it
disconnects the wallbox). Point it at local
ws://localhost:9000/<ocppSecret> or a deployed
wss://…/<ocppSecret>. Gateway is optional — pick one only to couple EV load
into Modbus inverter/meter registers. HTTPS pages cannot open ws://localhost
(mixed content); use npm run site locally for a local CSMS.