Delta Tau PMAC2A-PC/104 - Manual (Page 21)

PMAC2A PC104 Hardware Reference Manual
Machine Connections 15
DAC Output Signals
If PMAC is not performing the commutation for the motor, only one analog output channel is required to
command the motor. This output channel can be either single-ended or differential, depending on what
the amplifier is expecting. For a single-ended command using PMAC channel 1, connect DAC1+ (pin
29) to the command input on the amplifier. Connect the amplifier’s command signal return line to
PMAC’s GND line (pin 48). In this setup, leave the DAC1- pin floating; do not ground it.
For a differential command using PMAC channel 1, connect DAC1 (pin 29) to the plus-command input
on the amplifier. Connect DAC1- (pin 31) to the minus-command input on the amplifier. PMAC’s GND
should still be connected to the amplifier common.
To limit the range of each signal to ±5V, use parameter Ix69. Any analog output not used for dedicated
servo purposes may be utilized as a general-purpose analog output. Usually this is done by defining an
M-variable to the digital-to-analog-converter register (suggested M-variable definitions M102, M202,
etc.), then writing values to the M-variable. The analog outputs are intended to drive high-impedance
inputs with no significant current draw. The 220
Ω output resistors will keep the current draw lower than
50 mA in all cases and prevent damage to the output circuitry, but any current draw above 10 mA can
result in noticeable signal distortion.
Example:
Pulse and Direction (Stepper) Drivers
The channels provided by the PMAC2A PC/104 board or the Acc-1P board can output pulse and
direction signals for controlling stepper drivers or hybrid amplifiers. These signals are at TTL levels.
Amplifier Enable Signal (AENAx/DIRn)
Most amplifiers have an enable/disable input that permits complete shutdown of the amplifier regardless
of the voltage of the command signal. PMAC’s AENA line is meant for this purpose. AENA1- is pin 33.
This signal is an open-collector output and an external 3.3 k
Ω pull-up resistor can be used if necessary.