LedControl Touch – UV LED control with touch display and Modbus

Measured centrally under UV-LED module M, wavelength 385 nm, power 100%, reference: bottom surface

A Modbus message consists of the address, the function code, the data field and the CRC. The address states which slave device is addressed, the function code determines the operation - reading or writing, for example - and the data field contains register addresses and values. A selection of the registers:

Modbus TCP is the extension of the protocol for communication over Ethernet networks. The LAN and web interface option provides it and replaces the RS485 interface.

Besides Modbus, the LedControl Touch can be controlled with short ASCII commands. A selection:

The test and control software shows the channels with intensity and status, switches them individually, sets timers and presets and logs the communication with the device.

A distance of 10 to 20 mm between the LED module and the target surface gives a particularly high uniformity of the irradiation. To optimize the homogeneity we recommend choosing the emitting area about 10 to 20 mm larger than the area to be irradiated. Where the demands on uniformity are lower, the distance can be increased and a larger area illuminated.

The diagram shows the relative irradiance along the X axis for distances from 10 to 100 mm; the emitting area is shaded grey. At the nominal distance the profile stays flat across the emitting area and drops at its edge; the greater the distance, the wider and lower it becomes. These are orientation values - they depend on the size, the wavelength and the distance.

For monitoring UV LEDs we recommend our calibrated UVA+ sensors. They are available as PLC sensors and for our hand-held radiometers such as the RMD.

For high irradiance and high temperatures we offer the XT sensors.

The latest generation of UVB and UVC LEDs stands out with significantly increased efficiency and improved operating stability compared with earlier types. Advances in cooling technology, semiconductor architecture and optical extraction have led to a longer service life and a better energy yield. Although their efficiency and power still remain below those of UVA LEDs, UVB and UVC LEDs have caught up considerably.

With the UV-LED iSFL we offer high-power UVA and, for the first time, new UVB and UVC LEDs alongside it. For disinfection applications we supply the wavelengths 265, 272, 275 and 280 nm; between 265 nm and 285 nm the modules reach an irradiance of 100 mW/cm². Please ask us for the wavelength that suits your application.

To make machines safe and to meet the requirements of the machinery directive 2006/42/EC, safety functions are needed in the controls. Usually the required performance level PLr is determined for every safety function. This is where the first difficulty with UV installations begins: the severity of the injury, the frequency and duration of exposure and the avoidance of the UV hazard have to be determined.

In the short term, UV exposure of the skin leads to erythema, elastosis and skin cancer; exposure of the eye can lead to photokeratitis, conjunctivitis and cataractogenesis. Skin cancer is a severe and usually irreversible injury.

Directive 2006/25/EC on artificial optical radiation permits regular exposure up to a daily exposure limit of 30 J/m². The severity of the injury can therefore be reduced through the duration and the intensity of the exposure without having to achieve absolute zero exposure: if the limit is observed, healthy adults can be expected to be exposed repeatedly without acute harmful effects. In the event of a fault, a short exposure may cause a reversible injury such as a slight erythema. The boundary is not reliable, however, and measures and safety functions are needed in every case.

Measurements are possible on existing installations; during the planning phase they are not, or only with additional effort, which is why a higher PLr is often demanded. This is exactly what the LedControl Touch and the PLready option are for - already at the planning stage.

The PLready safety option is suitable up to PL category 4 according to EN ISO 13849-1 and SIL 3 according to EN 62061, provided that cross-faults in the control of the LED module and in the sensor circuit can be excluded.

It works with a safety extra-low voltage (SELV) of 48 VDC that is safely separated by an external circuit and can switch the LED modules off completely in the event of a fault.

The optional shutdown for the performance level separates the LED modules through an external contact:

A two-channel safety door monitoring with automatic start is shown in the following example. Compared with simply separating the DC voltages, the advantage is the monitoring of the external contactors. The example is suitable up to category 4, PL e (EN ISO 13849-1) or SIL 3 (EN 62061), provided that cross-faults in the control of the actuator and in the sensor circuit can be excluded.

The device emits UV radiation and blue light. UV radiation is invisible. Any visible light is only luminescence excited by the radiation; it is usually much weaker than the exciting UV radiation. The irradiance of the device is several hundred times stronger than that of sunlight.

UV radiation can cause cataracts in the lens of the eye and inflammation of the retina. Always wear suitable UV protective goggles when operating the device. UV-A also causes skin discolouration and skin ageing; use suitable clothing, gloves and further personal protective equipment - depending on the irradiation dose.

The devices are designed and classified according to DIN EN 62471:2009-03 "Photobiological safety of lamps and lamp systems"; the UV-LED modules fall into risk group 3. Do not look into the LED and do not expose the skin to the UV radiation permanently.

We are glad to support you in setting up UV workplaces and with the risk assessment according to DIN EN 14255:2005.

Four preconfigured versions: S for one module, 4S for four, L for one large module, 2L for two. Customized versions on request.

Scope of delivery: the iSFL UV-LED module, the LedControl Touch, a cable of 3 to 10 m and the manual. Please state the wavelength and the options with your order.

The modules come in the sizes XS, M and L, each for UVA/VIS or for UVB/UVC.

Please state the required wavelength with your order; it is not part of the order number. The peak wavelength lies within ± 5 nm.

The LAN and web interface replaces the RS485 interface; control is possible through LAN, Modbus RTU or as ASCII communication.

The UV protective goggles protect the eyes and the surroundings from stray radiation; the emitters are classified in risk group 3 according to DIN EN 62471.