| Operation: | Static and dynamic operation can be distinguished. Most multi beam light barriers are available with both operating modes. Static: An interference of one light beam by the part which is detected causes a change at the output of the amplifier which continues until the interference disappears, i.e. until the object leaves the light barrier. Pulse length is as long as the part stays in the light barrier (lingering period of part). Dynamic: An interference of one light beam by the part which is detected causes a change at the output of the amplifier which is independent of the lingering period and disappears when pulse length is finished (also refer to pulse length which is adjustable between 1 ms. and 100 ms.). Only moving parts can generate a signal with a dynamic light barrier (dynamic operation!). Parts which stay in the light barrier cannot be detected, e.g. parts which stay inside the cross section of a dynamic operating sensor! Dynamic / static: Sensors with both operating modes can detect moving parts generating an output signal with adjustable pulse length between 1 ms. and 100 ms. Additional parts can be detected which stay inside the cross-section of e.g. a frame light barrier. This feature expands the possibilities for industrial applications especially for multi beam light barriers, e.g. when ejected stampings must be detected by a sensor behind the tool. |
| Accuracy: | The smallest part that can be detected by a sensor using highest sensitivity. |
| Output: | PNP: Resistance will be connected with ground of power supply. In active state the output transistor of the amplifier switches resistance to the (+) - pole of power supply. PNP operating sensors are state of the art and used in many industrial applications and SPC's. NPN: Resistance will be connected with the (+) - pole of power supply. In active state the output transistor of the amplifier switches resistance to ground of power supply. |
| Operating voltage: | Every single and multi beam light barrier has a voltage range of either 12 - 24 VDC (-5%/+20%) or of 12 - 30 VDC (-5%/+10%), depending on type. All amplifier types have a voltage regulator which achieves a voltage range as mentioned above and makes independent from fluctuatings of power supply. Today 24 VDC is standard operating voltage in industrial ambiance and applications. |
| EMC-Test: | VESTER light barriers and amplifiers were subjected extensive and detailed tests and measurements in relationship with the EMC-guideline 89/336/EWG, especially with regards to the EMC-interference according to IEC-801-2/4. As sensors do not have their own power supply all measurements were put through with VESTER tool monitoring systems and additional connecting cables and accessories. A certification (CE) is related to the various types stated in the documentation. |
| Function principle: | VESTER single and multi beam light barriers operate as infrared and laser one-way sensors. Transmitter and receiver are arranged in a common optic axis. The PG- and PGL-types have separate housing for the optic elements. Fork and frame light barriers have a common housing for transmitter and receiver. Both transmitter and receiver are selected for highest sensitivity to achieve the required accuracy and reliability. |
| Housing: | Every fork and frame light barrier is manufactured of anodised aluminium which achieves high stability for many years and protects against electromagnetic radiation. The optoelectronic elements are protected with scratch-proof hard glass. Every light barrier can be fastened in many different ways either with holes in the body or with special rails and protective frames/protective housings. |
| Pulse length: | Amplifier types for dynamic/static multi beam barriers enable to increase short signals by potentiometer up to 100 ms (adjustable range between 1 and 100 ms., standard value 10 ms.). This is an important feature for many applications with SPC's which cannot detect short signals during their cycle time. Most single beam light barriers of ...-S2-type can optional be provided with an adjustable pulse length. For applications when high speed counting is required pulse length must be considered according to the max. frequency. |
| Function: | For one-way light barriers with digital operating amplifiers the active function is as follows: bright function: The output transistor of the amplifier is active if a sufficient quantity of light is affected from the receiver. There is no part between transmitter and receiver. dark function: The output transistor of the amplifier is active if the receiver is sufficiently interfered. One light beam must be interfered with multi beam light barriers. A part stays between transmitter and receiver. With most light barriers the function can be changed according to the corresponding application (bright-dark function). |
| Circuit: | Single beam as well as multi beam light barriers are available with two amplifier types. Constant light amplifier: The constant light amplifier supplies the transmitter of the light barrier with direct current which affects the receiver as direct (not modulated) light rays. Therefore light barriers with constant light amplifier are especially qualified for high speed counting. For special applications amplifiers with a frequency of more than 5 KHz are available. Standard sensors have a frequency of > 1 KHz. The dependence on external light of the constant light amplifier affects the result whenever intense external light or ambient light is to be expected. Direct radiation into the receiver must be avoided by appropriate measures The plug-in amplifier types S2-... for single beam light barriers provide an indication for contamination and adjustment. In standard operating mode a red LED changes according to the status of the light beam. Red LED off: light beam is not interfered, adjustment between transmitter and receiver is OK. Red LED on: light beam is interfered by an object. In the case of contamination or if transmitter and receiver are not adjusted correctly the red LED is on permanently especially when the light beam is not interfered by an object. Chopped light amplifier: The chopped light amplifier supplies the transmitter of the light barrier with modulated light of an evaluate frequency. The receiver detects only the light which belongs to this frequency. Therefore the chopped light amplifier is independent against ambient light and achieves a high reliability against contamination. Its main field of application is with transmitter-receiver infrared light barriers, in which high distances between transmitter and receiver unit are to be implemented, as well as with fork light barriers with small aperture and corresponding high resolution. Due to the switching frequency, the chopped light amplifier is also appropriate for very fast moving and small objects. Maximum switching frequency 4 KHz. The status of light beam is indicated by a yellow LED at amplifier types in separate housing as follows: Yellow LED off: light beam is interfered Yellow LED on: light beam is not interfered This indication is independent of the bright-dark function. |