PMAC Product Guide Note: The PMAC installed in an ISA bus can either use the bus ±12V power supply or an external ± 15V power supply. It is recommended that an external power supply is used that will keep the digital and analog circuits separate and that will provide better electrical noise isolation to PMAC. 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). In the Universal PMAC-Lite, these inputs can be kept isolated from other circuits. A power supply from 12 to 24V connected on pin 9 of J8 can 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. Note: The Flags screen of the EZ-PMAC Setup Software allows the setup and monitoring the end-of-travel limit flags.
These flags must be disabled or properly connected to allow motion of the corresponding motor. 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 closed switch is used. If a proximity switch is needed instead, use a 15V normally closed to ground NPN sinking type sensor. 28 Machine Connections