CY545 Stepper System Controller
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*** Warning *** Warning *** Warning ***
Although the CW_LIMIT and the CCW_LIMIT signals allow the CY545 to
provide some protection to systems that accidentally run into limits, they should
NOT be used as the only protection if reaching the limits could endanger
operators or damage the equipment.
Unexpectedly hitting a limit implies some failure, and no component, including
the host computer or CY545, can be fully trusted in this situation. Automatic
recovery from a limit should be used with extreme caution, since the system
could perform the recovery, then run back into the limit again, if the original
cause of the failure has not been fixed.
The best protection in cases where the system has failed, is to disable the
power to the stepper motor drivers. This will allow the motors to stop moving the
load, even if they are commanded to continue stepping. The cause of failure
should then be determined and fixed before the motors are energized again.
JOG Mode Operation
The CY545 provides manual stepper control through the JOG signal. This signal is tested when
the CY545 is not executing a command or performing another motion. This is a special signal,
because it is checked for one of three different states and is both an input and an output.
When the line is left floating, so the CY545 can drive it both ways, the jog function is disabled,
and stepping only occurs when the CY545 is commanded to take a motion.
When the line is driven low, the CY545 will jog the motor in the clockwise direction. The CCW
signal will change state, if required, to select this direction.
When the line is driven high, the CY545 will jog the motor in the counter clockwise direction.
Again, the CCW signal will change state, if required, to select this direction. Note that the signal
level on the JOG line matches the stepping direction selected by the CCW signal.
The CCW signal is restored
to its original state when
each jog single-step finishes.
Normally, the JOG signal will
be connected to a three
position, center-off switch.
One side of the switch will be
connected to ground, while
the other side is connected to +5 volts. Jogging is enabled in each direction by pushing the
switch from the center position to one side or the other. This is shown in the figure.
When jogging, the CY545 will take one step, then check for any new command inputs. If a new
command is available, it will be executed, otherwise the JOG signal will be tested again. When
the CY545 is idle, the effect of driving the JOG line is for the CY545 to take repeated single
steps. Note that the checking for new commands during jogging allows you to issue CY545
© 2002 Cybernetic Micro Systems
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Chapter 16 - Timing and Control
ETC [ ETC ]
