ADLINK Technology MPC-8164, User Manual

Page: 119 / 311

Operation Theory 107
4.2 The motor driver interface
The card provides the INP, ALM, ERC, SVON, and RDY signals
for a servomotor driver control interface. The INP and ALM are
used for feedback of the servo driver status, ERC is used to reset
the servo driver’s deviation counter under special conditions, VON
is a general purpose output signal, and RDY is a general purpose
input signal. General purpose means that the processing of the
signal is not a hardware built-in procedure. The hardware pro-
cesses INP, ALM, and ERC signals according to pre-defined rules.
For example, when receiving ALM signal, the card stops or decel-
erate to stop output pulses automatically. However, SVON and
RDY act like common I/Os.
4.2.1 INP
The processing of the INP signal is a hardware build-in procedure,
and it is designed to cooperate with the in-position signal of the
servomotor driver.
Usually, servomotor drivers with a pulse train input has a deviation
(position error) counter to detect the deviations between the input
pulse command and feedback counter. The driver controls the
motion of the servomotor to minimize the deviation until it
becomes 0. Theoretically, the servomotor operates with some time
delay from the command pulses. Likewise, when the pulse gener-
ator stops outputting pulses, the servomotor does not stop imme-
diately but keeps running until the deviation counter is zero. Only
after stopping does the servo driver send out the in-position signal
(INP) to the pulse generator to indicate the motor has stopped run-
ning.
If you do not enable INP checking by
_8164_set_inp()
func-
tion, the motion completion from
_8164_motion_done()
func-
tion and INT signal are raised after all pulses are sent.
If you enable INP checking by
_8164_set_inp()
function, the
motion completion from
_8164_motion_done()
function and
INT signal will not be raised until the INP signal from servo driver
is raised.
The in-position function can be enabled or disabled, and the input
logic polarity is also programmable by the “inp_logic” parameter of