# \[APP\]\[Pro\] Alfen Pro NG9xx via Modbus **URL:** \ **Category:** Apps\ **Tags:** app, community-app\ **Created:** [October 27, 2026, 2:13pm UTC](https://community.homey.app/t/app-pro-alfen-pro-ng9xx-via-modbus/161408 "2026-10-27T14:13:37Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Ruud\_Schellekens](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/ruud_schellekens/32/79224_2.png) [@Ruud\_Schellekens](https://community.homey.app/u/Ruud_Schellekens)\ **Post date:** [October 27, 2026, 2:13pm UTC](https://community.homey.app/t/app-pro-alfen-pro-ng9xx-via-modbus/161408/1 "2026-10-27T14:13:38Z")
# Alfen Pro NG9xx Control and monitor your **Alfen Pro-line (NG9xx)** EV charging station from Homey over your local network using **Modbus TCP**. No cloud, no back-office in between, and a charging current that stays within what your main connection can safely deliver. [Alfen Pro NG9xx | Homey](https://homey.app/nl-nl/app/com.ruud.alfenmodbus/Alfen-Pro-NG9xx/test/) ## What it does - **Monitor** : voltage and current per phase, charging power, total energy, energy of the current session, and a readable status like the one on the charger’s own display. - **Control** : set the maximum charging current with the Homey slider, a Flow action, or let a smart-charging app such as **SlimLaden** do it through the target power. - **Grid protection** : reads the per-phase power of a Homey Energy Dongle (P1) and limits the charging current to the room that is actually left on your main connection. If the P1 data is missing or looks wrong, charging falls back to a safe current you set yourself, never to “no limit”. - **1/3 phase switching** : if your station has the phase-switching relay, charge on 1 phase, 3 phases, or let the app switch automatically based on the power that is requested. - **Dual-socket stations** : every socket becomes its own Homey device. Developed and tested on a dual-socket Alfen station (firmware 4.10, ACE Service Installer 3.4.10-130) with SlimLaden. ## Requirements - Alfen charger on the **NG9xx platform** with **Active Load Balancing**. This needs a **license key from Alfen** ; without it Modbus can’t be enabled. - An account for the **ACE Service Installer** (installer login, request via [support.alfen.com](http://support.alfen.com)). - Charger and Homey on the same network (wired is recommended for the charger). - Optional but recommended: a **Homey Energy Dongle (P1)** for the grid protection. ## Step 1: enable Modbus on the charger (ACE Service Installer) There is no separate “Modbus on/off” switch. Modbus is enabled by the combination below. 1. Select your charger and log in. 2. **Load balancing \> Active balancing** : tick _Active Load Balancing_ (this needs the Alfen license), set _Data Source_ to **Energy Management System** , and set the **Safe current (A)**. Tick _Allow single-/multiphase charging_ if you want phase switching and your charger has the relay. The safe current is what the charger uses on its own when it stops receiving commands from Homey. A value below 6 A effectively stops charging in that situation (I use 4 A). 3. **Load balancing \> TCP/IP EMS** (this menu item appears once step 2 is done): set _Mode_ to **Socket** and keep _ValidityTime_ at **60** seconds. That is all there is to set. If you don’t see _Energy Management System_ as a data source, or the _TCP/IP EMS_ menu item doesn’t appear, your charger most likely doesn’t have the Active Load Balancing license yet. If your charger is managed by an operator through a back-office, they may control or lock these settings, and in Energy Management System mode the charger follows the external controller, so please check with them first. ## Step 2: add the device in Homey 1. _Add device \> Alfen Pro NG9xx_. The charger is found automatically on your network and its IP address is kept up to date if it changes. 2. The app currently offers **socket 1 and socket 2** for every station. With a single-socket charger just keep socket 1. 3. Link your P1 dongle: open the new device, then **menu \> Repair** , and pick your Energy Dongle. You can change this any time the same way. (This is why the app asks for access to the Homey API: it is only used to read the power and voltage of that one device.) ## Settings - **Connection** : IP address, socket (Modbus unit ID, 1 or 2) and poll interval (default 10 s). - **Charging** : _Max charging current (A)_, a fixed ceiling for cable, installation or personal preference. This is not the grid protection. - **Phases** : _Charging phases_ (1 phase, 3 phases, or Automatic) plus the two switch thresholds for Automatic mode. - **Grid safety limit (P1)**: _Max grid current per phase (A)_ is the limit of your main fuse per phase, and _Fail-safe current_ is used when P1 data is missing. ## The four “maximum current” layers They only ever lower each other, never raise: 1. What you want right now (target power slider, SlimLaden, a Flow). 2. Your own fixed ceiling (_Max charging current_). 3. The calculated _Safe max current_ from your P1 meter, with the fail-safe as fallback. 4. The charger’s own _Safe current_ (set in ACE), used if Homey stops sending commands for 60 seconds. ## Troubleshooting - **Device unavailable** : Modbus is most likely not enabled yet (see step 1), or the IP address is wrong. The charger accepts **at most 2 simultaneous Modbus TCP connections** , so don’t run other Modbus tools next to the two Homey devices. - **“Safe max current” always shows the fail-safe value** : the P1 dongle isn’t linked (use _Repair_) or its data is stale. - **Phase switching does nothing** : your charger needs the relay, and _Allow 1- and 3-phased charging_ has to be enabled in ACE. - **A car that only uses 1 phase** (for example an Ampera-e) gets one third of the requested power in 3-phase mode. The app detects this and falls back to 1 phase for the rest of that session. ## Disclaimer This is an unofficial community app and is not affiliated with Alfen. The grid protection is an aid, not a guarantee. You remain responsible for your installation and for setting the limits correctly, and you use the app at your own risk. Questions, remarks or bugs are welcome in this topic. If you report a problem, please mention your charger model, firmware version and app version. ---
**Author:** ![Ruud\_Schellekens](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/ruud_schellekens/32/79224_2.png) [@Ruud\_Schellekens](https://community.homey.app/u/Ruud_Schellekens)\ **Post date:** [October 27, 2026, 4:55pm UTC](https://community.homey.app/t/app-pro-alfen-pro-ng9xx-via-modbus/161408/2 "2026-10-27T16:55:11Z")
Thanks for that! I’ve installed it. It came up with two devices, don’t know why cause I have a single line charger? The adding of the devices got stuck. After exiting the installation process it does show two devices, but both of them inresponsive. I noticed the prerequisites to have modbus enabled and active load balancing in energy management mode. My charger is partly controller by the back-office integration, I checked ACE but couldn’t find where to enable modbus. Could you help me out on which settings in ACE need to be changed? ---
**Author:** ![Ruud\_Schellekens](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/ruud_schellekens/32/79224_2.png) [@Ruud\_Schellekens](https://community.homey.app/u/Ruud_Schellekens)\ **Post date:** [October 27, 2026, 4:57pm UTC](https://community.homey.app/t/app-pro-alfen-pro-ng9xx-via-modbus/161408/3 "2026-10-27T16:57:46Z")
**Two devices:** the app currently always offers socket 1 and socket 2. With a single-socket charger, just keep “socket 1” and remove the other one. I’ll fix the pairing so it detects the number of sockets. **Modbus:** There is no separate Modbus switch in ACE. Under _Load balancing \> Active balancing_ tick _Active Load Balancing_ and set _Data Source_ to _Energy Management System_; then under _TCP/IP EMS_ set _Mode_ to _Socket_ (validity time 60 s). If you can’t select Energy Management System or the TCP/IP EMS menu item doesn’t appear, the Active Load Balancing license is most likely missing. Since the charger is also managed through a back-office integration, please check with your operator whether they allow this, because the charger then follows the external controller. I’ve written all this down step by step in the first post of this topic.