
MAN1029-10-EN_EXL10_XL10P_UM
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9.3.7 HSC Functions
The high-speed input on the EXL10/XL10 PRIME contains many optional tasks, all of which can be
disabled, or set to an internal pre-assigned register (Assigned %Q) or to one of the external High-speed
inputs (External Input #1, 2, 3 or 4). Al
so, they can be set as an “overflow interrupt” or “underflow
interrupt” meaning that they will occur when either the Overflow or Underflow, input has been
activated.
Disable
: When the disable function is active it will “disable” the high
-speed inputs and no longer count
pulses until it is re-enabled
Latch
: When the Latch function is active it takes the current value of the Accumulator and moves it into
the “Latch Value” register.
Preload
: When the pre-load function is active, it will take the value
from the “Preload” register and put
it into the “Accumulator” for the corresponding counter.
Clear
: When the clear function is active, it will move a value of “0” into the Accumulator for the
corresponding counter
Marke
r: When the marker function is enabled, it acts as a dynamic enable/disable for the Disable, Latch,
Preload, and Clear functions. Therefore, if the marker is enabled and “Assigned %Q” is selected, then
both the “Disable” and the “Disable Marker” bits need to be set high in order to disable
the high-speed
input. If the Marker is set for one of the inputs, then the input will need to be “High” in order to use any
of the Disable, Clear, Preload, or Latch functions.
9.3.8 Status Bits
There are three status bits (%I registers for each high-speed counter)
Overflow Flag
: This status bit turns high when the Accumulator “overflows”, it moves from
4,294,967,295 (-
1 if Signed) to 0, this bit can be reset with the “Output Reset Bit”, see
Table 9.4.
Underflow Flag
: This status bit turns high when the
Accumulator “underflows”, it moves from zero “0”
to 4,294,967,295 (-
1 if Signed), this bit can also be reset with the “Output Reset Bit”.
NOTE
: For the Overflow and Underflow flag registers, if using some sort of counter that counts both up
and down, going over the threshold to go negative, triggers the underflow, and then going back over the
threshold back into positive numbers will trigger the positive register to go active.
High Speed Out
: This register will follow the high speed output assigned to the counter, it is important
to note that this register is still populated within the scan time so the value in this register may not be
up to date depending on the timing of the output (it should be up to date within one scan).