ADLINK Technology cPCI-8168, User Manual

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Operation Theory 75
4.6 The Comparaters
There are 5 counter comparators of each axis:
1. Positive soft end-limit comparator to command counter
2. Negative soft end-limit comparator to command counter
3. Command and feedback error counter comparator
4. General comparator for all counters
5. Trigger comparator for all command and feedback
counters
4.6.1 Soft end-limit comparators
There are two comparators for end-limit function on each axis. We
call them for the soft end-limit comparators. One is for plus (posi-
tive) end-limit and the other is for minus (negative) end-limit. The
end-limit prevents a machine crash during travel. Soft limit can be
used instead of a real end-limit switch. Notice that these two com-
parators only compare the command position counter. Once the
command position is over the limited set inside the positive or neg-
ative comparators, it will stop moving as it touches the end-limit
switch.
4.6.2 Command and feedback error counter comparators
This comparator is only for command and feedback counter
errors. This comparator can be used to check if the error is too
large. When this condition is met an action can be set, such as
generating interrupt, immediate stop, and deceleration to stop.
4.6.3 General comparator
With general comparator the source of comparison can be chosen
from command, feedback position counter, error counter or gen-
eral counter. The compare methods could be chosen by equal,
greater than or less than with direction or directionless. Once the
condition is met the action can also be chosen from generating
interrupt, stop motion or others.