User manual

Section 13: Instrument Control Library (ICL) Series 3700 System Switch/Multimeter Reference Manual
13-40 3700S-901-01 Rev. C / July 2008
channel.connectrule
Remarks,
continued
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.
Cold switching is highly recommended. When switch channels are both opened and
closed, the command executes not less then the greater of either the open or close
settle times of the indicated switch channels.
In general, the settle time of single commands which open and close switch channels
depend on a number of factors, such as card type and channel numbers. However, the
opening and closing of two sequential channels including no others, can be
guaranteed as follows:
channel.BREAK_BEFORE_MAKE open settle time + close settle time
channel.MAKE_BEFORE_BREAK open settle time + close settle time
channel.OFF maximum of open settle time and close settle time
This behavior is also affected by connect.connectsequential (on page 13-
40).
Example
Sets the connect rule in the system to chanel.BREAK_BEFORE_MAKE:
channel.connectrule =
channel.BREAK_BEFORE_MAKE
channel.connectsequential
Attribute
Indicates if the connection rule is sequential or not.
Usage
To read the connect sequential value:
sequential = channel.connectsequential
To write the connect sequential value:
channel.connectsequential = sequential
Set sequential to:
channel.OFF or 0 to disable sequential connecting
channel.ON or 1 to enable sequential connection
Remarks
If sequential connecting is enabled, the list of channels or analog backplane relays
close sequentially. This allows for a deterministic time for the command to be
executed. For example, if each channel takes 4ms to close, closing 3 channels takes
12ms. However, if connectsequential was OFF, it may take 4, 8, or 12ms
depending on if the card can close multiple relays at once.
This attribute applies to switch cards like EMR and reed relay cards.
Default setting and channel.reset sequential connection is channel.OFF.
Changing this attributes settings causes an existing scan list to be rebuilt based on the
new setting.