Mach-DSP User’s Manual
Document Number: MACH-DSP-9021
Page 65
www.ScannerMAX.com
IMPORTANT NOTICE ABOUT TTL OUTPUTS AND LASER SAFETY
Since the TTL Outputs are delivered to external machinery and devices through a
connector, it is possible that the connector can become unplugged, and then the
external machinery may be led to believe that the monitored condition remains
permanently in a safe state!
Likewise, since the TTL Outputs are delivered via optical isolators, these optical
isolators do not conduct any current when power is not applied to the Mach-DSP.
Therefore external machinery will not receive the correct signaling based on a non-
powered Mach-DSP servo driver, possibly leading to an unsafe condition.
Moreover, all of the parameters of the TTL Outputs are saved with each scanner tuning.
If you specify a
Condition
in one scanner tuning, but a different
Condition
in another
scanner tuning, then the machinery that is monitoring TTL Outputs may be fooled into
believing that the scanning or system is in a safe state when it isn’t…
And finally, the TTL Output signals themselves are ultimately controlled and activated
by software, which (although we make every effort in our programming and testing to
ensure reliability) may have unknown flaws.
For these reasons and more, you should not rely on the TTL Outputs from the
Mach-DSP as the
sole
means of ensuring laser safety.
Indeed, Pangolin makes a separate product called
PASS
, which monitors the power
supply, scanner position signals, the actual measured laser power, and other laser
projector health-related phenomenon, and does so using circuits implemented in a
redundant fashion so that even if one or more circuits fail (either external or internal to
PASS), the PASS system will ensure that the overall projection system fails safe.
If you are interested in ensuring the greatest degree of laser safety in your product, you
should take a look at PASS. Overall information about it, including links to the PASS
manual can be found here:
http://pangolin.com/PASS/
