Measurement Computing USB-DIO24/37, Руководство пользователя

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Chapter 3
Functional Details
Components
The USB-DIO24/37 has the following components, as shown in Figure 3-1.
ƒ 37-pin I/O connector
ƒ USB connector
ƒ LED
LED
37-pin I/O connector
USB
Connector
Figure 3-1. USB-DIO24/37 components
37-pin I/O connector
The 37-pin connector provides 24 digital I/O, one counter, six ground, and two 5V power connections.
ƒ
The digital I/O is configured as two 8-bit and two 4-bit ports based on the 82C55 specification. You
can configure each port independently for input (default) or output.
ƒ The CTR signal is the input to the 32-bit external event counter. The internal counter increments
when the digital input level transitions from low to high. The counter can count frequencies of up to
1 MHz.
ƒ The six ground (
GND
) connections are identical, and provide a common ground for all USB-
DIO24/37 functions.
ƒ The two power connections draw power from the USB connector. The +5 pin is a +5 volt output that
is supplied by the computer.
Caution!
The +5 V pin is an output. Do not connect to an external power supply or you may damage
the USB-DIO24/37 and possibly the computer
3-1