User's Manual

PMAC User Manual
Input/Output: Connecting PMAC to the Machine 45
Optically Isolated Dedicated Digital Input Flags (JMACH Port)
Each channel of PMAC has four dedicated digital inputs on the machine connector: +LIMn, -LIMn
(overtravel limits), HMFLn (home flag), and FAULTn (amplifier fault). These inputs are typically
assigned to a motor as a set for dedicated use as flags by addressing them with the motor I-variable Ix25.
Those flags not used for the dedicated purposes may be used as general-purpose inputs with the
assignment of an M-variable.
Flag Wiring
All of these flag inputs must be shorted to the zero-volt reference voltage for the circuit (usually AGND),
allowing current to flow through the LEDs in the opto-isolator, in order to be considered in a zero state.
The current flow to 0V just needs to be broken to put the flag in its 1 state; no external pull-up is required,
although it will not hurt. For an electronic switch, an open-collector output is usually used. For a
mechanical switch, an open/closed contact between the flag pin and 0V is usually used.
Overtravel Limit Inputs
When assigned for the dedicated uses, these signals provide important safety and accuracy functions.
+LIMn and -LIMn are direction-sensitive overtravel limits that 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 the opposite of what many people would consider intuitive.
That is, +LIMn should be placed at the negative end of travel, and -LIMn should be placed at the positive
end of travel.
Home Flag Input
Typically, the HMFLn input is used for homing or other registration functions through use of the PMAC
hardware position-capture feature. Encoder/flag I-variables 2 and 3 determine which signals and which
edges cause a capture.
Amplifier Fault Input
Typically, the FAULTn input is used as a signal from the amplifier that something is wrong. Ix25
controls whether a high signal or a low signal means fault.
For more details on the actions taken on these flags, refer to the Making Your Application Safe and
Synchronizing PMAC to External Events sections of this manual.
Flag Isolation
These inputs can be kept isolated from other circuits. If supplied from the analog supply voltage (A+15V)
and tied to analog ground (AGND), they will be isolated from the PMAC digital circuitry. If supplied from
a digital supply voltage (+12V) and tied to digital ground (GND), they will be isolated from the PMAC
analog circuitry. If supplied from a separate supply (OPTO+V; 12 to 24V) and tied back to the supply’s
own ground, they will be isolated from both the digital and analog circuitry. The setting of jumpers E89 and
E90 controls which power the flag circuitry, and therefore, which circuits it is isolated from.
Dedicated Digital Output Flags (JMACH, JEQU Ports)
PMAC has two dedicated digital outputs for each channel in the hardware configuration: the Amplifier-
Enable/Direction line (AENA/DIRn) and the Compare-Equals line (EQUn).
Amplifier-Enable/Direction Output
The AENA/DIRn output is an optically-isolated output tied to the same circuit as the dedicated digital
inputs. It can be kept isolated from the PMAC digital computation circuitry, from the PMAC analog
circuitry, or both.