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

Specific information about Pico and Modbus TCP

Modbus TCP can be used with the Pico if:

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

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:

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

Example Modbus

Example with: https://www.modbusdriver.com/modpoll.html

Change Pico Loadmanagement

modpoll.exe -r 0x206E -t 4:int -i -1 -m tcp -p 502 192.168.178.63 16000

Register of Meters and Modules

Register Addressing

Register of Pico chargers

Pico-Modbus TCP