Measurement Computing DaqBoard 3000USB Series - Manual (Page 74)

5-12 Counter Input Modes 887794 DaqBoard/3000USB Series User’s Manual
PULSEWIDTH: OPT2: Determines whether the pulsewidth is to be measured with a 16-bit (Counter
Low), or 32-bit (counter High) counter. Since pulsewidth measurements always have the “stop at the top”
option enabled, this option dictates whether the measurement has a range of 0 to 65535 ticks, or 0 to
4,294,967,295 ticks.
PULSEWIDTH: OPT4: Allows the mapped channel to gate the counter. When the mapped channel
is high, the counter is enabled to count. When the mapped channel is low, the counter is disabled, but
holds the count value. The mapped channel can be any other input channel.
PULSEWIDTH: OPT6: This allows the mapped channel’s pulsewidth to be measured instead of the
input channel. The mapped channel can be any other input channel (post debounce). This option allows
the counter to be used with any other input channel (post-debounce). If the channel’s input is used
elsewhere, for example, gating another counter, the counter for this channel does not need to go unused.
Pulsewidth and Timing mode Accuracy
The 3000USB Series board has the ability to measure the pulsewidth of an input and the time between any
two edges on any two inputs. The time ranges are similar to those shown for period mode except that
averaging is not available. The ranges given below reflect this.
Upper 16-bits of the 32-bit Counter Lower 16-bits of the 32-bit Counter
Range (S) Ticksize (nS) Averaging
Option
Range (S) Ticksize (nS) Averaging
Option
800 – 80000 20833.333 1 10m – 1 20833.333 1
80 – 8000 2083.333 1 1m – 100m 2083.333 1
8 – 800 208.333 1 100u – 10m 208.333 1
800m – 80 20.833 1 10u – 1m 20.833 1
Pulsewidth and Time Ranges for a 16-bit Value
Sampling error is less than 0.21%
Full 32-bit Counter
Range (S)
Ticksize (nS) Averaging
Option
10m – 80000 20833.333 1
1m – 8000 2083.333 1
100u – 800 208.333 1
10u - 80 20.833 1
Pulsewidth and Time Ranges for a 32-bit Value
Sampling error is less than 0.21%
Full 32-bit Counter <10 ppm Full 32-bit Counter <1 ppm
Range (S) Ticksize (nS) Averaging
Option
Range (S) Ticksize (nS) Averaging
Option
2 – 80000 20833.333 1 20 – 80000 20833.333 1
200m – 8000 2083.333 1 2 – 8000 2083.333 1
20m – 800 208.333 1 200m – 800 208.333 1
2m – 80 20.833 1 20m – 80 20.833 1
High Accuracy Pulsewidth and Time Ranges for a 32-bit Value
that has little sampling error (<10ppm, <1ppm)