Determining if Modbus‑TCP is enabled?

[JohnConnett]

I have a Sigenergy system with a SigenStor (3 x 5 kWh) and a Sigen Gateway HomeMax SP12K. Both have a hard-wired Ethernet connection to my LAN. Both are assigned static IPv4 addresses by DHCP.

Is there a way to determine if Modbus‑TCP is enabled? Using nmap -Pn -p1-1024 on both IPv4 addresses shows all ports are closed (conn-refused). Would port 502 be expected to be open if Modbus‑TCP is enabled?

I would like to avoid asking my installer to enable it if it is already enabled ...

[TypQxQ]

If the Modbus-TCP is enabled then the integration can connect and lists it as a new unit found.
If Home Assistant has not found it, then it is not enabled.

[TypQxQ]

You can also check the Home Assistant logs if it found the SigenStor inverter and what error it got if it wasn't able to connect.

[phatlewt]

If the battery was powered off and on, do you know if the modbus tcp server has to be re-enabled, or should it stay enabled?

[JohnConnett]

Many thanks! It wasn't enabled. I asked my installer to enable it and they did it remotely. The integration can now connect and find 4 devices and 180 entities.

I didn't supply the installer with the IPv4 address of my Home Assistant so I assume that anything on my LAN can connect to port 502 on the Sigenstor. From another system on my LAN:

jrc@skylon:~$ nmap -Pn -p1-1024  sigenstor
Starting Nmap 7.94SVN ( https://nmap.org ) at 2025-06-16 10:39 BST
Nmap scan report for sigenstor (192.168.199.46)
Host is up (0.026s latency).
rDNS record for 192.168.199.46: sigenstor.home.verminmedia.com
Not shown: 1023 closed tcp ports (conn-refused)
PORT    STATE SERVICE
502/tcp open  mbap

Nmap done: 1 IP address (1 host up) scanned in 4.77 seconds
jrc@skylon:~$

This may not work if an IPv4 address had been specified. No ports appear to have been opened on the Sigenergy Gateway.

[JohnConnett]

I think this answers my question.

[StroppyOz]

It will stay enabled (at least it has when I’ve ever cycled power on the unit). From: phatlewt ***@***.***> Sent: Saturday, 11 October 2025 11:13 AM To: TypQxQ/Sigenergy-Local-Modbus ***@***.***> Cc: Subscribed ***@***.***> Subject: Re: [TypQxQ/Sigenergy-Local-Modbus] Determining if Modbus‑TCP is enabled? (Discussion #86) If the battery was powered off and on, do you know if the modbus tcp server has to be re-enabled, or should it stay enabled? — Reply to this email directly, view it on GitHub<#86 (reply in thread)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/BPOKIDYSR5HJOZYR2NMCWDL3XBDQRAVCNFSM6AAAAAB7KKDZPKVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTINRVGE3TQNA>. You are receiving this because you are subscribed to this thread.Message ID: ***@***.******@***.***>>