Laser beta lasermike LS8000-3 - Manual (Page 47)

LaserSpeed 8000-3 Instruction Handbook
Interfacing with the LS8000-3
Part No. 93463 / Drawing No. 0921-01561 Page 47 of 221 Revision A (Sep 2007)
When the product enters the measurement area and triggers the switch, the
Material Present signal should activate. This causes the LS8000-3 to start
counting length at 0. When the product leaves the measurement area and the
Material Present signal deactivates, the LS8000-3 will calculate the final length
and the measurement is complete. If in Final Length mode, the LS8000-3 will
transmit the Final Length over the serial/Ethernet ports.
Dual Switch Configuration
Two optical switches can be connected in parallel in order to further increase
the precision of part-length measurements. This configuration is typically used
on discrete part measurements that are long and have a very tight length
specification. The LS8000-3 repeatability specification is ±0.02% of the
measured length.
Example:
A cut-to-length application has a product that varies from 14 ft. (4.27m) to 16
ft. (4.88m) in length, and has a tolerance of ±1/8 inch (±0.125in./±3.2 mm.)
The LS8000-3 repeatability specification for a 16 ft. length is a little more than
±1/32 inch (±0.97mm.) While this is better than the length specification, the
measurement variation is only about ¼ the length specification. Ideally, a
measurement instrument's variation should be 10X smaller than the
specification it is required to measure.
In order to improve repeatability, the LS8000-3's measured length can be
reduced by using two optical switches to gate the LS8000-3's measurements.
The LS8000-3 will only measure while the product blocks both optical
switches. In this case, since the minimum part length is 14 ft (4.27m), the
switches could be placed 13 ft (3.96m) apart. This will reduce the length that
the LS8000-3 measures to between 1 and 3 feet. The repeatability will then
be ±0.02% of 1-3ft instead of ±0.02% of 12-16ft. The new repeatability would
then be ±0.0072 inch (0.18mm.) Because the distance between the two
switches is fixed, this value can be added to each length measurement that
the LS8000-3 produces using the Length Reset Value Setting ($R
configuration setting.)
The optical switches should be arranged and wired as shown below: