Measurement Computing USB-CTR04 - Manual (Page 8)

USB-CTR04 User's Guide Functional Details
The USB-CTR04 pinout is shown in Figure 3.
Figure 3. USB-CTR04 pinout
LED indicators
The device has two LED indicators –
Status
and
Activity.
 The
Status
LED (top) turns on when the device is detected and installed on the computer.
 The
Activity
LED (bottom) blinks when data is transferred, and is off otherwise.
Refer to Figure 2 on page 7 for the location of these LEDs.
USB connector
The USB connector provides 5 V power and communication.
Counter I/O and gating
The USB-CTR04 has a counter input (
CxIN
), counter output (
CxO
), counter gate (
CxGT
) screw terminal for
each of its four counter channels.
Counter inputs can be read asynchronously under program control, or synchronously as part of a digital scan
group. In both cases, you can configure counters so that they:

get set to 0 after each read
 count up or down and then roll over at a user-set limit
 count until the user-set limit has been reached.
Counter inputs can concurrently monitor time periods, frequencies, pulses, and other event-driven incremental
occurrences directly from pulse-generators, limit switches, proximity switches, and magnetic pick-ups.
Counter outputs can be used to control or transmit signals to external devices, and also to
USB-CTR04 counter inputs, counter gates, or digital inputs. Counter outputs are commonly used in Totalize
mode .
Counter gates use input signals to clear a counter, change counter direction, or start/stop counting. Gate options
are software-selectable and are available when counting in Totalize mode.
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