Owner manual

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PLC COUNTERS
There are four event counters that are associated with the PLC. One of these counters functions as an up/
down counter. The other three counters operate as up-counters. The maximum count rate is approximately
100 counts per second (100 Hz). The up-counters all have upper trigger values associated with them. When
the count reaches this trigger value, the counter output will be set automatically to “1”. The count will
continue past the trigger level when more transitions occur on the Increment PLC Bit. However, as long as the
count is equal to or greater than the (up-counter) trigger level, the counter output PLC Bit will be “1”. Each
up-counter has a reset PLC bit associated with it to reset the count to “0”. The up/down counter has a preset
value that is loaded into the counter when the counter reset PLC Bit is set to a “1”. Special Control
Parameters hold the current count of the counters. As a result, the values are retained during a power-down.
In addition, you can enter a new value into the count or increment/decrement the value with the scroll keys.
The up/down counter has a down count trigger value and an associated output to indicate when the count is
less than or equal to this trigger level.
The position counters that are associated with Lead Encoder and Follower Encoder inputs are available for
monitoring as well as for use in the numerical comparators. These counters are also used to determine the
position error, which in turn drives the position loops. These counters count pulses for non-quadrature (x1)
encoders or count edges for quadrature (x4) encoders. When the position-counter count reaches (or
exceeds) the rollover value, the counter is reset to “0” (plus any count over the rollover value).