Connecting the data line (Modbus RTU)
| The tasks described in this section may only be carried out by a qualified electrician. |
The product can be connected to an external energy meter or an energy management system via Modbus RTU.
MENNEKES recommends using the data lines below:
- With a line length of 40 m, a network cable (CAT-6 / CAT-7) can be used. It can be useful to use a network cable so that your installation is ready to accommodate future developments. Not all wires are required.
- PROFIBUS cable
- For installation in the ground: Siemens PROFIBUS line, underground cable 6XV1830-3FH10 (manufacturer EAN 4019169400428)
- For installation without mechanical stress: Siemens PROFIBUS line 6XV1830-0EH10 (manufacturer EAN 4019169400312)
Data lines must not exceed a length of 100 m.
Connection
A shield clamp and two cable ties are needed to connect the data line. These are included in the delivery contents.
Attach shield clamp:
- Strip the data line by 8 mm at a length of 115 mm.
- Attach the shield clamp at the stripped point.
- Use a cable tie to fix the shield clamp in place at the jacket.
Connect the data line:
- Strip the data line.
- Strip the conductors 10 mm.
- Connect the protective shield to terminal 9 (XG2).
- Connect the twisted-pair cables to terminals 7 and 8 (XG2).
Terminal (XG2) | Connection |
|---|---|
7 | A |
8 | B |
9 | GND |
- Comply with the connection data.
- Use a cable tie to fix all wire pairs in place.
- Insulate the used wire pairs (contact guard).
Attaching termination resistors at the ends of the data line (optional)
If it is not possible to establish a stable connection with the Modbus subscribers, we recommend terminating both ends of the data line using 120 Ohm resistors. Terminating the ends will reduce reflections and increase communication stability. The need for terminating the ends of wires is dependent on the installation environment (e. g. cable length, number of Modbus subscribers). A general specification regarding the use of termination resistors can therefore not be provided.