Truma remote display DuoC

Reading time 4 minutes

Updated – April 24, 2023

The Truma remote display DuoC is used to display the status of the gas bottle being supplied, as well as the switching status of the Eis-Ex and the activation of the same.

Unfortunately, the Eis-Ex heater cartridge is either on or off depending on the switch position - completely independent of the outside temperature, even if you could save on electricity consumption.

This can be changed! Provided you have control via RaspberryMatic on a Raspberry Pi. When using an AIO Creator visualization, the bottle states and the ice-ex function can also be displayed on any cell phone or tablet.

This also eliminates the need for another hole in the furniture, as the control panel is no longer necessary, as is laying the wiring from the gas bottles to it.

Connection assignments

Ice Ex

• green – Plus 12 V**
• white – mass

DuoControl CS

• yellow – LED red ON (reserve – INH1)
• gray – nc
• pink – LED green ON (plus active)*

DuoC

• red – plus 12V
• blue – mass
• white – ground (Eis-Ex – white)
• brown – mass
• green – Plus 12 V (Ice-Ex) – INH0 - green*
• yellow – LED red ON (reserve – INL2 - yellow)
• gray – nc – (INL1 - Gray)
• pink – LED green ON (Normal – INL5 – brown)

The switch on the DuoC control panel is used to switch the DuoC on/off and to switch on the Eis-Ex. Since the gas bottle status should always be signalled, the switch-off function of the DuoC is unnecessary, as is switching on the Eis-Ex, which will be done depending on the temperature in the future. The LED display is replaced by the visualization.

Only the cables of the Eis-Ex, such as the switch for the gas bottle status detection, are routed gas-tight through a wall of the gas bottle box at a height of at least 50 cm, either by means of two screw connections (then the plugs must be cut off in order to... to be able to pass cables through it), or a 10 mm hole (through which both plugs are passed one after the other), which is then sealed gas-tight with silicone.

* These connections are required for status evaluation
** temperature-controlled switched plus

Material list

• Homematic 4-way relay module HM-LC-Sw4-W
• Homematic radio transmitter module HM-MOD-EM-8Bit
• Homematic temperature-humidity sensor HM-WDS10-TH-0
• 12V DC source near the gas bottle box

Implementation – theory

Regulator icing occurs at temperatures just above freezing during (high) gas extraction. When the liquid gas expands into the gaseous state, it generates cold, which, if the outside temperature is appropriate, causes the controller to freeze over and thus interrupt the gas supply.
For example, while the refrigerator is working perfectly and the gas heater is also operating without any problems, the additional gas extraction from the three-burner gas stove may trigger the icing of the regulator.

The outside temperature sensor continuously delivers the outside temperature values. For example, from 5 °C, the Eis-Ex heater cartridge should be switched on via a channel of the 4-way relay module and switched off when the outside temperature reaches 7 °C.

The status display, whether the first or second (reserve) gas bottle is still in operation, is recorded via the Truma® sensor connections. Depending on the operating status, either the green or red LED on the original control panel is switched on.
This respective (plus) signal is sent via the radio transmitter module at the connection INH0, or. INH1 (reserve) is fed in and programmatically evaluated and visualized.

When switching to reserve mode, an email add-on can be used to automatically send an email informing you about the switch and reminding you of the upcoming gas bottle change.

Implementation – practice

For mounting in a housing, the circuit board of the radio transmitter module is best soldered to a slightly larger epoxy hole grid circuit board, where the plus 12 V DC power supply is directly connected to the pin 16, ground at pin 12 (GND) connected, as well as a double stranded wire for the purpose of supplying power to the 4-fold relay module, continued on its screw terminals 1 (plus) and 2 (Minus).
A “flying” installation is also possible, but make sure that the button on the circuit board is not pressed by vibrations or constrictions and that the antenna does not get lost in the other cables.

Screw terminal 3 of the switching channel 1 receives plus 12 V DC via another cable. On screw terminal 4 of the switching channel 1 will be the green plus cable of the Eis-Ex, as well as another green cable that is on INH0 leads, connected. As soon as the EisEx is supplied with plus via the relay on channel 1 of the radio switching actuator, this triggers the signal input at the same time INH0, which is evaluated programmatically and used for visualization.

The hole grid board is provided with M3 holes at the appropriate fastening points on the housing, through which it is secured in a vibration-proof manner using spacers. The cable of the switching actuator of the DuoControl CS is led into the housing via a cable gland.

At INL1 of the radio transmitter module, the gray one turns on INL2 the yellow cable INL5 the pink cable INH0 the green cable is connected. The brown, white and blue cables are connected together to the ground cable and the red cable to the positive cable.

The 4-fold relay module is attached to a suitable location with two diagonally opposite screws, next to which is the housing with the radio transmitter module.

Implementation – program

The program works without scripts.

• System variables of type to be created Logic value
  – IceEx – (A / OUT OF)
  – GAS_GK – (OK / reserve)

The following conditions can occur:

• Gas ok + EisEx off (binary 223)
• Gas ok + EisEx on (binary 222)
• Gas Reserve + EisEx off (binary 219
• Gas Reserve + EisEx on (binary 250)

These binary output values, which reflect the different switching states at the logic inputs, are evaluated as follows and the corresponding variables (for visualization) are set:

Implementation visualization

Since two DuoControl CS are installed here, one in the front gas box (GK) and one in the rear garage (HG) for the two bottles that supply the generator, two displays are required.

The respective displays are triggered according to the variables set. The yellow indicator flashes yellow/red when switching to the reserve bottle, otherwise it lights up green. If the EisEx is switched on, the display lights up red and green when switched off.