The REG system devices require a 12 Vdc power supply and a BUS connection, therefore a total of 4 wires. The REG bus uses the EIA-485 standard (formerly known as RS-485), so the first choice is to use cables specifically created for this type of bus.
The ideal installation is given by a twisted and shielded cable specific for EIA-485 BUS, such as:
BELDEN, 9841 (see https://www.belden.com/products/Cable/Electronic-Wire-Cable/RS-485-Cable)
CEAM, CPR 6003
TASKER, C521
FANTON, ACS 9841
Note
These models are given as examples of cables that have the suitable electrical characteristics; the electrical designer will have to verify the compliance of the chosen cable with the specific needs of the system: type of installation, fire resistance, etc.; BELDEN in particular has a whole family of EIA-485 cables, suitable for any type of installation).
The use of this type of cable and compliance with the "IN-OUT" wiring is MANDATORY as shown in the following image:
PHOTO TBD
Furthermore, it is important to underline that:
the devices order (REG-DIN-8/REG-EXP-8/REG-TH etc.) is NOT important, they must not be connected in any particular order
each device must be addressed and there cannot be two components with the same address
if the address is changed using a dip switch to any of the components, the power supply must be switch OFF and then ON again for the new address to be acquired
being the MASTER, REG-DIN-8 has no address
the 12 Vdc power cable and the bus cable (A and B) must NOT share the electrical conduits with the 230 Vac
Attention
if a cable is actually used as indicated, the shielding (in the following drawing highlighted in blue) must be connected ONLY IN ONE POINT to the zero of the power supply and where the cable is interrupted, to allow the connection of the various devices (in the example below a REG-DIN-8, a REG-EXP-8, a REG-THL sensor and a REG-OTG), the shielding must be spliced, but NOT connected to anything:
PHOTO TBD
The BUS cable that connects the devices (master, I/O expansions, combined temperature and humidity sensors, displays) as mentioned before MUST be wired "in/out"; do not create backbones or star connections:
PHOTO TBD