Using The Usb-6525 As A Ttl Output Device; Event Counter - National Instruments USB-6525 User Manual And Specifications

Using the USB-6525 as a TTL Output Device

Event Counter

© National Instruments Corporation
Figure 10 shows a signal connection example for a TTL-level application
with an external supply voltage of +5 V.
USB-6525
Figure 10. TTL Device Signal Connection Example
When the SSR is open, a small amount of current flows through R
output voltage is close to 5 V, a logic high. When the SSR is closed, current
flows through R and the output voltage is close to 0 V, a logic low.
L
Choose an R value small enough to provide the necessary source current
L
but large enough to reduce sink current and to avoid consuming
unnecessary power. Many TTL-level applications use an R
You can configure PFI 0 (an alias to P1.7) as the source for a 32-bit counter.
In this mode, the device counts low to high transitions on P1.7. The counter
can be armed and disarmed and the count can be read or reset through
software. For more information about event timing requirements, refer to
the Specifications section. Refer to your software documentation for more
information about counter programming techniques.
To External
+5 V Supply
P0.x A
P0.x B
13 USB-6525 User Guide and Specifications
R = 5 kΩ
L
V
OUT
Isolated
Ground
and the
L
value of 5 kΩ.
L