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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:

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:

image-20240225-175903.png

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:

image-20240225-175942.png

  • 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

if the installation needs do not allow for in-out wiring (houses on several floors for example) it is possible to install signal repeaters/splitters (code RIP-RS485) which allow the bus to be split correctly:

PHOTO TBD

  • The BUS cable must NOT be closed in a loop, it must ALWAYS be OPEN!

PHOTO TBD

  • some very large systems may require multiple power supplies, in these cases the references (zero) of all the 12 Vdc power supplies of the regulation system must be short-circuited:

PHOTO TBD

Note

The choice to have multiple power supplies may depend on:

  • by the fact that there are so many components of the system that a single power supply could not support them all

  • by the fact that the components (even though they are not many) are very distant and therefore the voltage drop along the line is such that it is necessary to put a second power supply at the other end

  • from both previous situations

As regards the dimensions of the power cables:

  • The sizing depends on how the various elements are distributed along the bus, and therefore it is impossible to give general guidelines

  • Indeed, the problem is not the capacity of the power supply, which is almost always overabundant, but the voltage drop along the line

  • Assuming the worst case (such as that all the current, 5A for the PS60 for example, is absorbed at the end of the line, say even just 30 meters) leads to unrealistic situations, with cables with too large sections

If you want to give general indications for example for an apartment/small house where the expansions and the master are close and inside the electrical box with their power supply and along the bus line in the apartment there are only sensors and displays, you can consider a power supply cables from 2x1 mmq up to 50 meters.

For different situations (very large homes on several floors, expansions spread across different electrical box)  it would always be advisable to have this part sized by a qualified designer, who takes into account where the various devices are located along the line and how much each one absorbs.

BUS ERRORS TROUBLESHOOTING

Bus errors refer to lack of communication between the components of the REG system and if they occur the Bus Err led on the Master is ON and fixed. Before continuing with what is indicated below, check that the bus wiring has been done as indicated in the previous part.

If communication is restored, the Err Bus led disappears if you press the Reset button from RegConfig (Configuration Page 1) or from the REG display, press the OK button in the menu Information – Alarms/Bus Error – Address Bus Error until the error does not return to zero. Alternatively, power OFF and ON the REG-DIN-8.

When a fixed bus error occurs:

  1. Check the wiring and the power supply of the device (below 9 Vdc the components may not be able to support communication via bus)

  2. Try to reverse A and B

  3. Check that A and B are not shorted

  4. Check that the address of the component is correct. If you change it, remember to turn the power off and on again otherwise it will not be acquired

  5. Check that you have also configured the correct address on the REG

  6. Verify that all project components are present, installed and powered ON

  7. Exchange the component with another working one

  8. If the component works at this point, the problem is the bus wiring

  9. Otherwise the component can be damage (check points 4 and 5 again)

The best test is to connect the component that does not communicate with a master external to the system and check its operation.

Interference presence (flashing/intermittent bus error)

On some systems, sporadic bus errors may occur on a certain number of rotating components. In this case, to resolve it, it is advisable to insert the 3 k Ohm or 4 kOhm polarization resistors between – and A and between + and B on the master (in the REG-DIN-8 batches from 22170 of July 2022 onwards the resistors are on board the PCB).

In these cases, the bus, if not engaged in communication, could be positioned at an undefined voltage (floating) and this condition could lead to the slaves not identifying the start bit sent by the master. Then the slave misses the transmission and does not respond.