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