Modbus TCP
With Modbus TCP, the measured values of a device can be queried directly via the network connection. No detour via the cloud is necessary.
Requirements
To activate Modbus TCP you need a smart-me Professional subscription
Supported devices
The following smart-me devices support Modbus TCP:
3-phase meter telstar all versions
Kamstrup module from firmware version 8.0 (Info: This module cannot offer stable Modbus communication without a constant Internet connection.)
Pico EV-Charger All versions
Activate Modbus TCP
Log in on the smart-me website or in the smart-me app.
Select the desired device
Click on "edit"
Switch on "Modbus TCP" under the "Advanced Settings"
Specific information about Pico and Modbus TCP
Modbus TCP can be used with the Pico if:
The Pico is not in a load management group.
The Pico is in a load management group and the master (determined automatically).
Modbus TCP is deactivated for all slaves in a load management group, as they also do not have their own IP-address.
If the Picos in a load management group want to be read or controlled, we recommend to use the Rest API.
Find the address of the device
To read a device with Modbus TCP, you need to know the address of this device. The smart-me devices obtain the IP address from the local DHCP server. There are two ways to find the address:
1. Enable DNS
The easiest way to connect to a smart-me device in the local network is to enable the automatic DNS
Log into the smart-me website or the smart-me app.
Select the desired device.
Click on ‘Edit’.
Activate ‘Enable DNS’ under ‘Advanced settings’.
You can select the device’s public IP address or internal IP address as the address:
Public IP
The public IP address is used. This is usually your router’s IP address.
Internal IP
This is the smart-me device’s local IP address. It can be used to access the smart-me device if you are in the same network.
Background
The ‘dns-me’ service allows users to connect directly to a smart-me device without knowing its IP address. If the ‘DNS address’ is enabled for a smart-me device, its local or public IP address is automatically assigned to a DNS name (e.g. smart-me_123456.dns-me.com).
smart-me uses the dns-me.com service for this purpose.
After activation a ping can be carried out using the DNS address specified by the unit (command prompt).
Command: ping smartme_serialnumber.dns-me.com
In response, you will receive the evaluation of the test including the IP-address of the device.
2. Configure DHCP / Router Server
Another way to find out the IP address of a smart-me meter is to look it up on your router or DHCP server. There is currently no way to find out the MAC of a device using smart-me software.
Data transmission
Modbus TCP Protokoll
TCP Port: 502
Functions
The smart-me Meter supports the following Modbus functions:
Read Holding Register (Code 03)
Register Addressing
For historical reasons the address in Modbus is 1 lower than the internal register address. So the start address has to be (Registeraddress - 1)
Example Modbus Telegram (read serial number)
Request: 00 04 00 00 00 06 01 03 1F FF 00 02
Response: 00 03 00 00 00 07 01 03 04 00 00 18 9F
