Delta Tau PMAC2A-PC/104 - Manual (Page 20)

PMAC2A PC104 Hardware Reference Manual
Machine Connections 14
Flags Power Supply
Each channel of PMAC has five dedicated digital inputs on the machine connector: PLIMn, MLIMn
(overtravel limits), HOMEn (home flag), FAULTn (amplifier fault), and USERn. A power supply from 5
to 24V must be used to power the circuits related to these inputs. This power supply can be the same
used to power PMAC and can be connected from the TB1 terminal block or the JMACH1 connector.
Overtravel Limits and Home Switches
When assigned for the dedicated uses, these signals provide important safety and accuracy functions.
PLIMn and MLIMn are direction-sensitive over-travel limits that must conduct current to permit motion
in that direction. If no over-travel switches will be connected to a particular motor, this feature must be
disabled in the software setup through the PMAC Ix25 variable.
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. Usually, a passive normally close switch is used. If a
proximity switch is needed instead, use a 5 to 24V normally closed to ground NPN sinking type sensor.
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 I9n2. However, for the following reasons, the same type of switches used
for over-travel 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.
Motor Signals Connections
Incremental Encoder Connection
Each JMACH1 connector provides two +5V outputs and two logic grounds for powering encoders and
other devices. The +5V outputs are on pins 1 and 2; the grounds are on pins 3 and 4. The encoder signal
pins are grouped by number: all those numbered 1 (CHA1+, CHA1-, CHB1+, CHC1+, etc.) belong to
encoder #1. The encoder number does not have to match the motor number, but usually does. Connect
the A and B (quadrature) encoder channels to the appropriate terminal block pins. For encoder 1, the
CHA1+ is pin 5 and CHB1+ is pin 9. If there is a single-ended signal, leave the complementary signal
pins floating – do not ground them. However, if single-ended encoders are used, check the settings of the
resistor packs (see the Hardware Setup section for details). For a differential encoder, connect the
complementary signal lines – CHA1- is pin 7, and CHB1- is pin 11. The third channel (index pulse) is
optional; for encoder 1, CHC1+ is pin 13, and CHC1- is pin 15.
Example: differential quadrature encoder connected to channel #1: