B&B Electronics USB-4751/4751L user manual 2 I/O Connector Signal Description

3.2.2 I/O Connector Signal Description

Table 3.1: I/O Connector Signal Description

Signal	Ref.	Direction	Description
PA<0~7,	GND	Input/Out-	Digital input/ output port A, channel
10~17>		put	0~7 & channel 10~17.
PB<0~7,	GND	Input/Out-	Digital input/ output port B, channel
10~17>		put	0~7 & channel 10~17.
PC<0~7,	GND	Input/Out-	Digital input/ output port C, channel
10~17>		put	0~7 & channel 10~17.
+5V_OUT	GND	Output	+5V DC power
C<1,2>_Out	GND	Output	Output pins of counter/ timer 1 and 2
C<1,2>_Gate	GND	Input	Gate control pins of counter/ timer 1
			and 2
C<1,2>_In	GND	Input	External clock source of counter/ timer
			1 and 2
INT_Out	GND	Output	Interrupt output. This pin changes to
			logic 1 whenever the
			USB-4751 generates an interrupt, and
			returns to logic 0 when the interrupt is
			cleared.
GND	-	-	Digital ground

3.2.3 LED Indicator Status Description

The USB Module is equipped with a LED indicator to show the current status of the device. When you plug the USB device into the USB port, the LED indicator will blink five times and then stay lit to indicate that it is on. Please refer to the following table for detailed LED indicator status information.

Table 3.2: LED Indicator Status Description

LED Status	Description
On	Device ready for work
Off	Device not ready to work
Slow Blinking (5 times)	Device initialization
Fast Blinking	Device working
(Depends on data transfer speed).

USB-4751/4751L User Manual 14