Specifications

The 34945EXT only supports
Common Positive coil drive, so
you must connect the common
connection on the switch to
the +VR lines on the Y1155A,
and the switch must use
Common Positive drive circuits.
Position Indicators
These are just Digital Inputs
that respond to the same
voltage level as the coil drive
or TTL signals. The 34945EXT
allows inverting the polarity
of the position indicator input,
so you can indicate the desired
logic level. For Continuous Mode
channels, you can wire the Coil
Drive channel to the Position
Indicator channel. If you have
position indicator signals
coming from the switch, you
can hook them to the position
indicator channel. +VR and
Ground are available on the
Y1155A board to drive
position indication.
LED Drive
Each LED senses the position
indicator logic level. Sense
inversion can be set, so the LED
goes ON or OFF, dependent upon
the logic sense of the Position
Indicator Channel. Each vertical
pair of pins represents 1 of 16
channels. The +V, Anode, side
is the bottom row, and the
Cathode side is the top row
which is driven by the Position
Indicator. For paired channels,
the OPEN/CLOSE would cause
LEDs to be lit between both
socket headers (e.g. Channels
1/11), instead of being paired
together as you would find in
the Y1150A through Y1154A
boards.
Example: driving an Agilent 33311B
Microwave Switch
The 33311B is a latching
switch that automatically
disengages current (Current
Interrupts) after about 25 ms.
Therefore, you can use Pulse
Mode or Continuous Mode on
this type of switch. Once the
switch changes state, you can
monitor the drive lines to
detect the state of the switch.
The Common Positive terminal
(C+) is connected to the +VR
on the card for open collector
operation. Connection 1 (C1)
is wired to the OPEN side,
Channel 1; Connection 2 (C2)
is wired to the CLOSE side,
Channel 11. Channels 1 and
11 are paired together using
the Web Server. Drive wires are
connected to the associated
Position Indicators. The sense
logic can be inverted, if neces-
sary to achieve the desired
results. The leftmost
LED in
each bank will light when open-
ing and closing the switch.
If this were a normally open
switch with a single coil, you
would only connect to a single
channel and use continuous
mode. Everything would be
wired the same except there
would only be two wires
coming from the switch.
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