Using The Data Queue For Real-Time Communication - Keithley 708B Reference Manual

Models 707B and 708B Switching Matrix Reference Manual
Coordinating overlapped operations in remote groups
Errors occur if you send a command to a node in a remote group running an overlapped operation. All
nodes in a group must be in the overlapped idle state before the master node can send a command
to the group.
Use the waitcomplete command to:
•
Group leader and master node: To wait for all overlapped operations running in the local group
to complete
•
Master node only: To wait for all overlapped operations running on a remote group to complete
on the TSP-Link network
•
Master node only: To wait for all groups to complete overlapped operations
For additional information, see
The following code is an example on how to issue the waitcomplete() command from the master
node:
-- Waits for each node in group N to complete all overlapped operations.
waitcomplete(N)
-- Waits for all groups on the TSP-Link network to complete overlapped operations.
waitcomplete(0)
The group leader can issue the waitcomplete command to wait for the local group to complete all
overlapped operations.
The following code is an example of how to issue the waitcomplete command:
-- Waits for all nodes in a local group to complete all overlapped operations.
waitcomplete()

Using the data queue for real-time communication

You cannot access the reading buffers or global variables from any node in a remote group while a
node in that group is performing an overlapped operation. You can use the data queue to retrieve
data from any node in a group performing an overlapped operation. In addition, the master node and
the group leaders can use the data queue as a way to coordinate activities.
The data queue uses the first-in, first-out (FIFO) structure to store data. Nodes running test scripts in
parallel can store data in the data queue for real-time communication. Each Models 707B and 708B
has an internal data queue. You can access the data queue from any node at any time.
You can use the data queue to post numeric values, strings, and tables. Tables in the data queue
consume one entry. A new copy of the table is created when the table is retrieved from the data
queue. The copy of the table does not contain any references to the original table or any subtables.
To add or retrieve values from the data queue and view the capacity, see the
Library (ICL) command reference
707B-901-01 Rev. A / August 2010
waitcomplete() (on page 7-243).
(on page 7-8).
Section 6: Instrument programming
Instrument Control
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