11.3.2 Individual Response Time and Safety (Minimum) Distance
When calculating individual safety distance for each emitter/receiver pair, the pair’s position in the cascade affects its
response time, which then affects its safety distance (see safety distance formulas in
Calculating the Safety Distance
on page 28). The individual method results in an optimized safety distance for each light screen in the
cascade, while ensuring that each sensor pair is located at an adequate distance from the hazard.
The response time depends on how far the light screen is from the machine control. Each light screen position in the
cascade, starting from the first light screen in the cascade that is connected to the machine control, increases the light
screen’s response time by 2 ms. To calculate response time (Tr) for individual placement of each emitter/receiver pair in the
cascaded system, use the following formulas:
Position #1: Tr
(cascade1)
= Tr
Position #2: Tr
(cascade2)
= Tr + 2 ms
Position #3: Tr
(cascade3)
= Tr + 4 ms
Position #4: Tr
(cascade4)
= Tr + 6 ms
11.3.3 CSSI Response Time
When contacts (such as an E-stop button) are connected to the
CSSI cascaded receiver input, the CSSI response time is 40 ms
plus 2 ms for each additional light screen (slave pairs).
This is an example of a four sensor pair, cascade system with the
individual response times calculated for each of the sensor pairs.
Light screens of other lengths/resolutions will have different
response times.
The 23 mm resolution, 560 mm EZ-SCREEN LS emitter/receiver
pairs each begin with a response time of 11.6 ms. The pair in
position #1 (connected directly to the machine control), maintains
its 11.6 ms response time. Response time for the second pair in the
cascade circuit increases by 2 ms, to 13.6 ms; for the third pair by 4
ms, to 15.6 ms, and for the fourth pair by 6 ms, to 17.6 ms.
Emitters
Receivers
EZ-SCREEN LS
Position #1
Machine
Control
EZ-SCREEN LS
Position #2
EZ-SCREEN LS
Position #3
EZ-SCREEN LS
Position #4
L4
L3
L2
L1
Tr
4
= 11.6 + 6 = 17.6 ms
E-Stop
(CSSI Input)
CSSI Response Time = 46 ms
Tr
CSSI
= 40 ms + (3 x 2 ms)
Tr
3
= 11.6 + 4 = 15.6 ms
Tr
2
= 11.6 + 2 = 13.6 ms
Tr
1
= 11.6 ms
Figure 45. Individual Response Time Calculation Example
11.4 Emergency Stop Buttons in Cascaded Systems
Cascadeable EZ-SCREEN LS receivers may be connected to one or more E-stop buttons. The button(s) must connect to
the end of the last receiver in the cascade, in place of the terminator plug. The connected E-stop button(s) will activate/
deactivate the OSSD outputs in all receivers in the cascade.
The number of E-stop buttons allowed in a series connection is limited by the total resistance per channel. The total
resistance is the sum of all contact resistance values in the channel, plus the total wire resistance in the channel. The
maximum total resistance per channel is 100 Ω.
EZ-SCREEN
®
LS Safety Light Screen
74
www.bannerengineering.com - Tel: +1.763.544.3164
