52 Rockwell Automation Publication 450L-UM001D-EN-P - December 2019
Chapter 4 Safety Function
Cascading and Blanking
When a 450L-E safety light curtain is installed for cascading, each cascading
450L-E pair functions as a standalone safety-light curtain pair with its OSSDs
connected in series to the host pair OSSDs. Therefore, if requested, it is necessary
to configure fixed blanking and/or reduced resolution in each cascaded pair. This
configuration is accomplished by inserting in each 450L-E receiver an 8-pin
450L-APR-MU-8 plug-in that the blanking functionality is provided. First, set
the DIP switches for the requested blanking function before you start assembling
the light curtain sticks. Then, align all pairs and secure the brackets. It is then
possible to teach each light curtain pair receiver with the Teach-In procedure. A
successful completion of the teach function changes the operating mode of that
pair only. During the teach-in process, the OSSDs of that pair and the OSSDs of
the host segment are off (0V). Connected Components Workbench software can
also be used to configure blanking for each cascaded pair.
Response Time
The response time, T
r
, of the light curtain is the time from when the protective
field of the light curtain is interrupted to when the safety outputs turn OFF. The
response time is affected by the light curtain features that are used in the
application.
Standard Response Time, T
s
The standard response time refers to the response time for standard on/off
application. The standard application includes the following:
•Any start mode
•All operating ranges
•All EDM settings
The standard application does not include the advanced features:
•Beam coding
• Blanking (fixed or floating)
•Cascading
• Multiple zones
•Muting
•Reduced resolution
For the purposes of determining the response time, floating blanking is
equivalent to reduced resolution.
Although muting is considered an advanced feature, muting has no effect on the
response time.
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