# Growatt MIN XXXX TL-XH + EW11 Modbus TCP instability ("Connection to modbus server closed")

**URL:** <https://community.homey.app/t/growatt-min-xxxx-tl-xh-ew11-modbus-tcp-instability-connection-to-modbus-server-closed/160290>\
**Category:** Questions & Help\
**Created:** [October 2, 2026, 8:12pm UTC](https://community.homey.app/t/growatt-min-xxxx-tl-xh-ew11-modbus-tcp-instability-connection-to-modbus-server-closed/160290 "2026-10-02T20:12:52Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Niels\_Wijnbergen](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/niels_wijnbergen/32/177179_2.png) [@Niels\_Wijnbergen](https://community.homey.app/u/Niels_Wijnbergen)\
**Post date:** [October 2, 2026, 8:12pm UTC](https://community.homey.app/t/growatt-min-xxxx-tl-xh-ew11-modbus-tcp-instability-connection-to-modbus-server-closed/160290/1 "2026-10-02T20:12:52Z")

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Hello everyone,

I’m looking for some help getting a stable Modbus TCP connection between my Growatt inverters and Homey Pro 2024.

**System setup**

- 46 × 420 Wp solar panels
- 3 × Growatt MIN inverters:
  - MIN 3600TL-XH
  - MIN 4200TL-XH
  - MIN 4600TL-XH

- All inverters connected through an Elfin EW11 RS485-to-WiFi gateway
- Unique Modbus IDs configured for each inverter
- Homey Pro 2024
- Using the Modbus TCP/IP app by Ronny Winkler

**What works**

After rebooting the EW11, everything works perfectly:

- Reading registers
- Writing registers
- Controlling active power via Register 3 (0-100%)

**The problem**

After running for some time (typically within an hour), communication becomes unstable and I start receiving the following error “Connection to modbus server closed” on write and read commands

**What I have already tried**

- Verified unique Modbus slave IDs
- Checked EW11 configuration against the Growatt Modbus protocol
- Placed a dedicated Wi-Fi access point very close to the EW11 to rule out Wi-Fi signal issues
- Reduced the polling frequency, increased polling frequency (to keep the modbus live)

**Questions**

1. Has anyone experienced similar issues with Growatt + EW11 + Modbus TCP?
2. Could missing RS485 termination resistors be the cause? I don’t have the start and end resistors in place of 120 ohm. Connection between the EW11 and 3 growatts is less then 2 meters.
3. Are there specific EW11 settings (packing time, timeout, TCP settings, heartbeat, etc.) known to improve stability?
4. Is there a recommended polling interval when communicating with multiple Growatt MIN XH inverters?

**Goal**

My goal is to dynamically control inverter output based on hourly electricity prices:

- Export when prices are positive
- Run approximately zero-on-the-meter around €0/kWh
- stop production when the effective export price becomes sufficiently negative

Any suggestions or experience with a similar setup would be greatly appreciated.

Thanks!

EW11 settings

Protocol: Tcp server

Socket settings:  
Local port: 502  
Buffer size:512  
Keep alive: 60s  
Timeout: 30s  
Protocol settings max accept: 3  
Security: disable  
Route: Uart

Serial port settings:  
Baud rate 9600  
Data bit 8  
Stop bit 1  
Parity None  
Buffer settings  
Buffer size:512  
Gap time:50

Flow control settings:  
Flow control: disable

Cli settings  
Cli: Serial string  
Serial string: +++  
Waiting time: 300

Protocol settings:  
Protocol: Modbus

Advanced settings in homey Modbus TCP app:  
IP address 192.168.1.246  
Port:502  
ID 1,2 or 3 (depending on which inverter)

Modbus options:  
Use write multiple registers function for sing register: no  
Prevent writing unchanged data: no

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<div class="post-metadata">

**Author:** ![smarthomesven](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/smarthomesven/32/79712_2.png) [@smarthomesven](https://community.homey.app/u/smarthomesven)\
**Post date:** [October 2, 2026, 8:41pm UTC](https://community.homey.app/t/growatt-min-xxxx-tl-xh-ew11-modbus-tcp-instability-connection-to-modbus-server-closed/160290/2 "2026-10-02T20:41:42Z")

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Hi @Niels_Wijnbergen ,  
Please report your issue in the app topic:

> [@\[APP\]\[Pro\] SolarEdge + Growatt TCP modbus](https://community.homey.app/t/app-pro-solaredge-growatt-tcp-modbus/45487):
>
> Purpose The difference of this app and the already existing solar panels app is that this app reads the data directly from the inverter. The solaredge api and others are mostly limited to 300 calls/ day, so you get only updates every 10-15 minutes. The modbus app receives data every few seconds. If you have the Solaredge energy monitor installed you can maximize your self-consumption and limit your exported power by using it. You can make flows based on your generated solar power, exported p…

.

> [@Niels\_Wijnbergen](#):
>
> Homey Pro 2024

Homey Pro 2024 does not exist. I assume you mean Homey Pro 2023?