Section 2: General operation
Models 707B and 708B Switching Matrix Reference Manual
2-82
707B-901-01 Rev. B / January 2015
Queries that return a list of channels
For queries that return a channel list parameter, the Model 707B or 708B separates the channels by a
comma or semicolon, depending on the command. When multiple channels are used in the query, the
information for the lowest numbered channel is listed first, increasing to the highest numbered
channel.
When multiple slots are used in the query, the information for the lowest slot number is listed first and
increases to the highest slot and channel.
Connection methods for close operations
You can dictate the order in which relays are opened and closed using the channel connection rule.
When the connection rule is set to break before make, the instrument ensures that all switch
channels open before any switch channels close. This behavior covers the most common
applications and is considered the safest connection rule because the tested device is
completely decoupled from the instrument. This is the default behavior. When switch
channels are both opened and closed, this command executes not less than the addition of
both the open and close settle times of the indicated switch channels.
When the connection rule is set to make-before-break, the instrument ensures that all
switch channels close before any switch channels open. This behavior should be applied
with caution because it will connect two test devices together for the duration of the switch
close settle time. When switch channels are both opened and closed, the command
executes not less than the addition of both the open and close settle times of the indicated
switch channels.
With no connection rule (set to
channel.OFF
), the instrument attempts to simultaneously
open and close switch channels in order to minimize the command execution time. This
results in faster performance at the expense of guaranteed switch position. During the
operation, multiple switch channels may simultaneously be in the close position. Make sure
your device under test can withstand this possible condition. When switch channels are
both opened and closed, the command executes not less than the greater of either the open
or close settle times of the indicated switch channels.
Cold switching is highly recommended.
Hot switching can dry weld reed relays such that they will always be on. Hot switching is
recommended only when external protection is provided.
The channel connect rule determines the order in which multiple channels are opened and closed on
the instrument. This attribute applies to electromechanical, reed, and solid state relay switching cards.
