NDC BETA LaserMike LaserSpeed Pro 8500-4, Инструкция по эксплуатации, Страница: 63 / 348

LaserSpeed Pro 8500-4 Instruction Handbook: Interfacing with the LS8500-4 4-15
Optical Switch Mode LS8500-4 Material Present Mode
Light Operate External Active Low
Dark Operate External Active High
When the product enters the measurement area and triggers the switch, the Material Present signal should
activate. This causes the LS8500-4 to start counting length at 0. When the product leaves the measurement
area and the Material Present signal deactivates, the LS8500-4 will calculate the final length and the meas-
urement is complete. If in Final Length mode, the LS8500-4 will transmit the Final Length over the seri-
al/Ethernet ports.
4.2.1.14 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 LS8500-4 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 LS8500-4 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 LS8500-4's measured length can be reduced by using two optical
switches to gate the LS8500-4's measurements. The LS8500-4 will only measure while the product blocks
both optical switches. In this case, since the minimum part length is 14ft (4.27m), the switches could be
placed 13ft (3.96m) apart. This will reduce the length that the LS8500-4 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 LS8500-4 produces using the
Length Reset Value Setting ($R configu-
ration setting) .