In the safety protection system of automation equipment, safety light curtains are standard. It uses infrared beams to build an invisible protective wall. Once a person or object breaks in, the equipment operation is immediately cut off to prevent accidents. However, many engineers have found a problem in actual use – the light curtain response time is slow, the equipment response is delayed, and even affects the efficiency of the production line.
So, where does the delayed response time of the safety light curtain come from? How to adjust it reasonably? Today we will talk about this seemingly “invisible” but technical detail that has a great impact on safety and efficiency.
First, understand the true meaning of “delay”
The so-called response delay is not that the light curtain is “broken” or “slowed down”, but the “delay action” set by the system during factory settings or installation and debugging – for example, when a person leaves the light curtain, how many milliseconds or seconds will it take for the equipment to resume operation.
This delay is intended to prevent accidental touches or back and forth movements from causing frequent start and stop of the equipment, but if it is set too long, the equipment will “stop and not rush to move”, wasting time.
Second, adjustment technique 1: Check the controller or PLC delay setting
Most safety light curtains are not used alone, but are connected to PLC or safety relays to work together. At this time, the response delay is usually set by the PLC program.
It is recommended to check whether there are the following settings in the program:
Delay output start time (delay ON)
Delay output shutdown time (delay OFF)
Hold time (Hold time) or buffer logic
If it is found that the setting time is greater than 200ms, it is recommended to adjust it to between 50~100ms according to the actual situation, which can generally significantly improve the response speed of the equipment.
Third, adjustment technique 2: Use high-speed reaction light curtains
Light curtains of different brands and models have different hardware response times. The response time of ordinary light curtains is between 20~30ms, while high-end models can reach 10ms or even less than 5ms.
If your application scenario is a high-beat station such as high-speed stamping, fast handling, and robot linkage, it is recommended to choose a product with a nominal response time of less than 10ms. The faster the hardware, the stronger the overall response capability of the system.
Fourth, adjustment technique three: Reasonably optimize the installation position and the number of beams
The more beams the light curtain has, the more data it processes, and the response time may be slightly longer. For some scenarios that do not require high-precision recognition, such as detecting the entire arm or human body passing through, it is actually unnecessary to choose too dense beams.
In addition, if the optical axis is installed too far or the alignment deviation is large, it may also cause the light curtain recognition to be unstable, so that the system automatically lengthens the response delay as a protection. This situation can be solved by simply re-adjusting the angle and distance.
