User`s guide

4 Using the System Utilities
92 Model N6705A User’s Guide
The I/O pins can be used to control both relay circuits as well as
digital interface circuits, as illustrated in the following figure.
For a complete description of the electrical characteristics of the
digital port, see Appendix A.
Digital In
Each of the seven pins can be configured as digital input only. The
ground reference for the input pins is Signal Common on pin 8.
The In field of the Digital I/O Properties window reflects the
condition of the external signal that is applied to the pin. The pin
state is not affected by the value of the digital output word.
Fault Out
Pins 1 and 2 can be configured as a fault-output pair. The Fault Out
function lets a fault condition on any output generate a fault signal
on the digital port. The following conditions will generate a fault
event: over-voltage, over-current, over-temperature, inhibit signal,
power-fail condition, or on some models, a power-limit condition.
When this function is selected, both pins 1 and 2 are dedicated to this
function. Pin 1 is the Fault output; pin 2 is common for pin 1. This
provides for an optically-isolated output. Note that Pin 2 must also be
connected to pin 8. Pin 2’s selected function is ignored. The Fault
output signal will remain latched until the fault condition is cleared.
You must also clear the protection circuit.
Inhibit In
Pin 3 can be configured as a remote inhibit input. The Inhibit In
function lets an external input signal control the output state of all of
the outputs in the mainframe. The input is level-triggered. The signal
latency is 5 microseconds. Pin 8 is common for pin 3.
B) Digital Interface CircuitsA) Relay Circuits
TTL, AS, CMOS, HC
Relay driver
Ports 0 - 6.
(contains internal
clamp diodes for
inductive flyback)
Coil
Current
0.1 A
Max.
16.5 V Max.
Digital Output
Ports 0 - 6
Digital Input
Ports 0 - 6
1 2 3 4 5 6 7
I
1 2 3 4 5 6 7
I
1 2 3 4 5 6 7
I