Chapter 4 Digital I/O Functionality
NI CVS-1450 Series User Manual 4-2 ni.com
TTL Inputs and Outputs
TTL is a fast-switching, 5 V, digital, signaling standard commonly used
forapplications that require high precision, such as camera triggering.
TTLinputs and outputs do not require a separate power supply.
Caution Do not connect voltage or current sources to TTL outputs. Doing so could
damage the CVS-1450 device.
Table4-1 summarizes the TTL inputs and outputs available on the
CVS-1450 device.
Isolated Inputs and Outputs
The isolated inputs and outputs on the CVS-1450 device have a separate
ground reference from the main CVS-1450 device supply, providing an
easy means to prevent ground loops that can introduce noise into a system.
You can apply signals up to 30V to the isolated inputs. The voltage swing
of the isolated outputs is determined by the Viso you supply on the
connector.
Note The isolated outputs have current-limiting protection circuitry. If this circuitry is
tripped, you can re-enable the outputs by restarting the CVS-1450 device or by toggling
the output state in the software.
Table 4-1. TTL Inputs and Outputs
Primary
Function
Input or
Output
Number
Avail able Signal Names
44-Pin DSUB
on CVS-1450
Device
Pin Number
37-Pin
Terminal Block
Pin Number
Trigger Input 2TTL Input 0
TTL Input 1
1
16
1
2
Timed Pulse Output 6 TRIG 1, Pulse 5
TRIG 2, Pulse 6
TTL Output 1, Pulse 1
TTL Output 2, Pulse 2
TTL Output 3, Pulse 3
TTL Output 4, Pulse 4
—
—
4
6
7
18
—
—
5
7
8
20
Watchdog Output 1 TTL Output 0 3 4
General-Purpose Output 3 TTL Output 5
TTL Output 6
TTL Output 7
19
21
22
21
23
24