Delta Tau Universal PMAC Lite, Справочник по аппаратуре

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Universal PMAC Lite
Machine Connections 34
Flags Power Supply (Optional)
Each channel of PMAC has four dedicated digital inputs on the machine connector: +LIMn, -LIMn
(overtravel limits), HMFLn (home flag), and FAULTn (amplifier fault). If the PMAC is ordered with
Option-1 (8-axis PMAC), these inputs can be kept isolated from other circuits. A power supply from 12
to 24V connected on pin 9 of J8 could be used to power the corresponding opto-isolators. In this case,
jumper E89 must be removed and jumper E90 must connect pins 1-2.
Overtravel Limits and Home Switches
When assigned for the dedicated uses, these signals provide important safety and accuracy functions.
+LIMn and -LIMn are direction-sensitive overtravel limits, which must be actively held low (sourcing
current from the pins to ground) to permit motion in their direction. The direction sense of +LIMn and -
LIMn is as follows: +LIMn should be placed at the negative end of travel, and -LIMn should be placed at
the positive end of travel.
Types of Overtravel Limits
PMAC expects a closed-to-ground connection for the limits to not be considered on fault. This
arrangement provides a failsafe condition and therefore it cannot be reconfigured differently in PMAC.
Usually a passive normally close switch is used. If a proximity switch is needed instead, use a 15V
normally closed to ground NPN sinking type sensor.
Jumper E89 and E90 must be set appropriately for the type of sensor used.
Home Switches
While normally closed-to-ground switches are required for the overtravel limits inputs, the home switches
could be either normally close or normally open types. The polarity is determined by the home sequence
setup, through the I-variables I902, I907, ... I977. However, for the following reasons, the same type of
switches used for overtravel limits are recommended:
•
Normally closed switches are proven to have greater electrical noise rejection than normally open
types.
•
Using the same type of switches for every input flag simplifies maintenance stock and replacements.