Overview of light curtains and muting
September 26 2024 | Blog Post, Venus Automation
As discussed in our two previous blog posts, safety light curtains from ReeR are an effective and innovative method to protect workers from hazardous environments. Light curtains create 2-dimensional planes of infrared beams that project between an emitter and a receiver. Dependent on the application, ReeR offer light curtains that are programmable, and trigger an output signal when a number of beams – consecutive or random – are obstructed. These output signals can then be used as logic input for safety PLCs and relays, such as controllers offered by Wieland and ReeR. For more detail on the general functionality of safety light curtains, read here.
For more specific applications of light curtains, where combinations of consecutive blocked beams are acceptable and do not pose as a hazard, light curtains need to discern what is permissible and what is not. This is where muting light curtains prove their value. Muting is the automated, partial suspension of light curtain beams. Light curtains, such as ReeR’s SAFEGATE, are offered with integrated muting arms. These muting arms can be oriented in either parallel or crossed patterns, such that obstructions of certain dimension/orientation can be recognised as hazardous or not. Onboard the muting arms are photocells, which project between one another to create a mutable area of the light curtain. The muting arm photocells belong to ReeR’s MICRON family of measurement light curtains, which is better explored here.
Muting will occur when the beams aboard the muting arms are blocked, effectively negating any output by the light curtain. This will allow only certain objects to pass through without triggering the light curtain’s safety output signal.
Depending on the automated process, objects passing through a light curtain may be repeatedly entering and exiting: passing back and forth through a light curtains protected area. Therefore, SAFEGATE muting arms are offered in configurations that for one-way and two-way muting. SAFEGATE light curtains from ReeR are also capable of long-range projection of up to 80 metres. Thus, they prove useful in large-scale industrial operations; safeguarding large spans of manufacturing areas without the need for additional light curtain’s in series.
Muting - Parallel or crossed beam?
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Selecting the right light curtain - safety or measurement?
It is very easy to be overwhelmed by the sheer number of models and options for safety light curtain, and measurement light curtain offered by ReeR. Though visually and operationally similar, there are some distinct differences in the specific applications each family of light curtain is best suited to.
Measurement Light Curtain (ReeR MICRON): Measurement light curtains from ReeR are highly versatile light curtains for industrial/manufacturing line measurement applications. They come in a variety of sizes (both length, and resolution) to effectively count and dimension objects that pass through it. In automated systems like conveyors and assembly lines, ReeR MICRON can be hardware/software configured to determine if measurements are within tolerance, objects are aligned and oriented correctly, and differentiate between different items on the line. They are offered in varying current and varying voltage output models, and one final model which has 2 antivalent outputs, and the option for programmability. ReeR MICRON measurement light curtains are NOT safety rated.
General Purpose Safety Light Curtain (ReeR EOS2, EOS4): ReeR’s EOS series of safety light curtain are a prolific and popular option for general purpose safeguarding. They come in a variety of sizes and resolutions for finger, hand and body protection (14, 30, 90mm). Furthermore, they are also offered in multi-beam configurations for access control. The EOS series are compact and straightforward to use, but do not feature any advanced control options such as muting. EOS light curtains are offered in safety categorys of Type 2 and Type 4. Thus, scenarios that call for higher standards of safety are well serviced by EOS safety light curtains.
Safety Light Curtain with Muting (ReeR SAFEGATE): ReeR SAFEGATE light curtains, as discussed in this blog, are highly capable, large scale safety light curtains. They are offered in various, often multibeam resolutions for large scale, industrial automation applications. Three of the four SAFEGATE safety light curtain models come native with integration options for muting. In applications such as conveyor belts, SAFEGATE safety light curtains will differentiate between shapes of acceptable dimensions and orientation. SAFEGATE light curtains have long range capabilities, and are well suited to creating long-distance, safeguarded areas that should not be crossed during machine operation.
Reer safegate light curtain models
Description
The SAFEGATE S series of light curtains from ReeR are a more basic, standard option for safety light curtains with muting. They come standrad with Type 4 SIL 3 safety ratings, and feature the most basic form of muting functions, two-sensor muting. The use of the SAFEGATE S is generally used for straightforward safety requirements, such as guarding dangerous areas and access points.
Specifications
Voltage: 24V DC
Connectivity: M12 12-pin, M12 5-pin
Outputs: 2 Static PNP outputs
Protected Height(s): 510-1800 mm
Resolution: multibeam or 40mm
Range: 60, 80m max (model dependent)
Reset: Automatic or manual
Protection: IP65/IP67
Benefits
SAFEGATE S has no advanced configurations like programmable muting sequences, but also provides the most streamlined and straightforward installation.
External Device Monitoring
SAFEGATE S light curtains make up for the lack of complex muting with provisions for External Device Monitoring (EDM). This feature is used to monitor the status of devices in a safety control system that are not directly linked, and thus enables monitoring of feedback, integrity of circuitry, redundancy, and the prevention of automatic restarting
Description
The SAFEGATE SM series of light curtains are the next step up in the SAFEGATE family. SAFEGATE SM light curtains come with integrated muting functions, hardware configurable models, and muting sensors for both one-way and two-way muting. The SM TRX models reduce the number of cabling required by using retro-reflective curtains to allow for simply a transmitter/receiver in one.
Specifications
Voltage: 24V DC
Connectivity: M12 12-pin, M12 5-pin
Outputs: 2 PNP 400mA outputs, failsafe, short circuit, and overload protection.
Protected Height(s): 310-2260 mm
Resolution: 30mm, 40mm, or 2/3/4 multi-beam
Range: 0-4 m, 0-8 m, 0-12 m (model dependent)
Benefits
SAFEGATE SM light curtains feature integrated muting sensors, with options for one-way muting with 2/4 sensors, and two-way muting with 4 sensors. This allows for a higher level of monitoring, and allows for logical muting and hardware programmability.
Muting Options
The SAFEGATE SM features more advanced muting options, with the ability to integrate the MA, and MZ muting bracket kits. The SAFEGATE SM allows for both one-way (entry or exit) and two-way (entry and exit) muting logic.
Description
The SAFEGATE SMO series of light curtains are another step up in the SAFEGATE family. SAFEGATE SMO light curtains come with integrated muting functions, hardware configurable models, and muting sensors for both one-way and two-way muting. Furthermore, this model of SAFEGATE comes with an onboard muting lamp. This allows for more direct insight into the functionality and operations of the light curtain in its day-today processes. The SMO TRX models reduce the number of cabling required by using retro-reflective curtains to allow for simply a transmitter/receiver in one.
Specifications
Voltage: 24V DC
Connectivity: M12 12-pin, M12 5-pin
Outputs: 2 PNP 400mA outputs, failsafe, short circuit, and overload protection.
Protected Height(s): 310-2260 mm
Resolution: 30mm, 40mm, or 2/3/4 multi-beam
Range: 0-4 m, 0-8 m, 0-12 m (model dependent)
Benefits
SAFEGATE SMO light curtains feature integrated muting sensors, with options for one-way muting with 2/4 sensors, and two-way muting with 4 sensors. The onboard muting lamp will also allow for more direct understanding/diagnosis of the light curtain. This allows for a higher level of monitoring, and allows for logical muting and hardware programmability.
Muting Options
The SAFEGATE SMO features more advanced muting options, with the ability to integrate the MA, and MZ muting bracket kits. The SAFEGATE SMO allows for both one-way (entry or exit) and two-way (entry and exit) muting logic.
Description
The final and most capable light curtain is the SAFEGATE SMPO. Similar to the SMO, the SAFEGATE SMPO features an onboard muting lamp for ease of monitoring. Expanding upon the hardware configured muting functions, the SMPO offers software programmability. Using the SAFEGATE Configurator (SCS), muting logic and partial muting is made capable using receiver programming. Not only does this allow for more flexibility in muting, but software capabilities also allow for digital monitoring.
Specifications
Voltage: 24V DC
Connectivity: M12 12-pin, M12 5-pin
Outputs: 2 PNP 400mA outputs, failsafe, short circuit, and overload protection.
Protected Height(s): 310-2260 mm
Resolution: 30mm, 40mm, or 2/3/4 multi-beam
Range: 0-4 m, 0-8 m, 0-12 m (model dependent)
Protection Rating: IP65/67
Benefits
SAFEGATE SMPO light curtains feature integrated muting sensors, with options for one-way muting with 2/4 sensors, and two-way muting with 4 sensors. The onboard muting lamp will also allow for more direct understanding/diagnosis of the light curtain. The SAFEGATE SMPO is software programmable, allowing for customisation of muting and output protocols for more specific and unique muting needs.
Muting Options
The SAFEGATE SMPO features more advanced muting options, with the ability to integrate the MA, and MZ muting bracket kits. The SAFEGATE SMO allows for both one-way (entry or exit) and two-way (entry and exit) muting logic.
More About Muting Arms
SAFEGATE MA muting arms are the more cost effective and simple muting option for SAFEGATE safety light curtains. They are enclosed muting sensors and can either be purchased as parallel or crossed beam. SAFEGATE MA muting arms are sold in options for both one-way and two-way muting logics. (L or T). MA muting arms are either always parallel or always crossed beam muted.
SAFEGATE MZ muting brackets are the more complex, and flexible muting option for SAFEGATE light curtains. They feature exposed photocells (ReeR MICRON M5), which can swivel and move to create custom angles and points where the beam projects from. The MZ L2XP for example, can be swivelled such that it is capable of either parallel or cross-beam In turn, this ability for customisation means that points of intersection for crossed beams can be customised, enabling muting for objects that are not centred between the beams. This extra option for more custom muting setups makes the SAFEGATE MZ favourable for end-users with specific requirements for muting safety light curtains.
The naming conventions for SAFEGATE muting accessories are broken down into 3-5 characters:
L/T: This refers to the muting logic of the light curtain, and the letter refers to the light curtain‘s geometry. L will be one-way muting, T will be two-way muting.
2/4: This refers to the number of beams used onboard each muting arm/bracket, with two beams being standard.
P/X: This refers to the beam configuration of the muting logic, where P stands for parallel beams while X represents crossed-beam muting.
TRX: TRX refers to retro-reflectors used. Rather than relying on an emitter and a receiver as separate units, TRX models combine the emitter and receiver into one unit, with the other curtain simply reflecting the beam from the emitter back to itself.
(TRX) V: These safety light curtain muting arms feature longer muting sensors, and are well suited for high speed conveyors.
(TRX) G: These safety light curtain muting arms have a shorter operative range, and are optimised for use in muting transparent items such as acrylic or glass.
SAFEGATE Muting Products
SAFEGATE cables
The CD series of light curtain cables are 5-pin/5-core cables compatible with ReeR safety light curtains. They are intended for use on the emitter side of the light curtain. These cables are offered in 5, 10, 20, and 25 metre lengths.
The CS12D series of light curtain cables are 12-pin/12-core cables compatible with ReeR safety light curtains. These light curtains are unique to normal receiver cables (which are 8-core), and are specified for receiver pins aboard SAFEGATE light curtain receivers. They are intended for use on the emitter side of the light curtain. These cables are offered in 5, 10, 20, and 25 metre lengths.
SAFEGATE Compatible PLCs and Relays
