Measurement Computing USB-1024HLS - Manual (Page 15)

USB-1024HLS User's Guide Functional Details
Ground terminals
The nine ground ( GND ) connections are identical, and provide a common ground for all USB-1024HLS
functions. Refer to the pinout diagram on page 3-2 for the location of the GND terminal.
Counter terminal
Pin 20 ( CTR ) is the input to the 32-bit external event counter. Refer to the pinout diagram on page 3-2 for the
location of this terminal. The internal counter increments when the TTL levels transition from low to high. The
counter can count frequencies of up to 1 MHz.
Pull-up/pull-down terminals
You can wire pin 11 ( Port C Pull-up / Pull-down ), pin 13 ( Port B Pull-up / Pull-down ), and pin 15 ( Port A Pull-
up / Pull-down ) to support a pull-up or pull-down connection. These terminals configure the internal 47K
resistors on the USB-1024HLS. Refer to the pinout diagram on page 3-2 for the location of these terminals.
These terminals are configured as open by default.
! To configure a pull-up connection for a specific port, wire the pull-up/pull-down terminal to a USB +5 V
terminal.
Figure 3-5. Pull-up connection for Port A
! To configure a pull-down connection for a specific port, wire the pull-up/pull-down terminal to a GND
terminal.
Figure 3-6. Pull-down connection for Port A
3-5