# \## Controlling Relay 0 and Relay 1 (Open Collector) from Node-RED on EasySolar II

**URL:** <https://community.victronenergy.com/t/controlling-relay-0-and-relay-1-open-collector-from-node-red-on-easysolar-ii/59394>\
**Category:** DIY\
**Tags:** beginner, easysolar\_all-in-one, vrm, cerbo-gx\
**Created:** [18 June 2026 08:45 UTC](https://community.victronenergy.com/t/controlling-relay-0-and-relay-1-open-collector-from-node-red-on-easysolar-ii/59394 "2026-06-18T08:45:28Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![JAM1](https://avatars.discourse-cdn.com/v4/letter/j/f4b2a3/32.png) [@JAM1](https://community.victronenergy.com/u/JAM1)\
**Post date:** [18 June 2026 08:45 UTC](https://community.victronenergy.com/t/controlling-relay-0-and-relay-1-open-collector-from-node-red-on-easysolar-ii/59394/1 "2026-06-18T08:45:28Z")

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Hello All,

I have sum up below the information for this post:

**Goal:**  
I want to control the two programmable relays (Relay 0 and the Open Collector K1) directly from Node-RED flows, without using VEConfig assistants.

**Setup:**

- EasySolar II 48/3000/35-32
- Venus OS 3.73 (integrated, no external Cerbo GX)
- Pylontech battery
- SmartSolar MPPT 250/70
- Node-RED via VRM Portal

**What I have already done:**

- Removed the “Programmable Relay” assistants from VEConfig to free up relay control
- Verified that relays work correctly when controlled via VEConfig assistants
- Confirmed Modbus TCP is enabled in Venus OS settings

**What I have tried:**

1. **dbus via Node-RED exec node:**  
Scanned all services for relay paths. The path /Relay/0/State does not exist on com.victronenergy.vebus.ttyS3 or com.victronenergy.system.  
Only relay-related paths found on vebus are internal protection relays (GridRelayReport, RelayTest, etc.).  
The path /Settings/Relay/0/InitialState exists on com.victronenergy.settings and is writable, but does not control the relay in real time.

2. **Modbus TCP:**  
Tested all Unit IDs listed in Venus OS (100, 225, 228, 229, 230).  
Only Unit ID 225 (Pylontech battery) responds correctly.  
All other Unit IDs, including 228 (VE.Bus/MultiPlus), return: GatewayPathUnavailable (Exception 10).  
Tested with both node-red-contrib-modbus and pymodbus directly.

3. **Custom Control node in Node-RED:**  
The MultiPlus-II appears in the device list, but no relay path is available in the Measurement dropdown.

**Questions:**

1. Is there a working method to control Relay 0 and the Open Collector K1 from Node-RED on an EasySolar II with integrated Venus OS?
2. Why does Modbus TCP return GatewayPathUnavailable for the VE.Bus Unit ID 228 on this integrated setup?
3. Is there a specific dbus path for real-time relay state control on this device?

Any help or pointer to documentation would be greatly appreciated. Thank you!