Model 2601B-PULSE System SourceMeter Instrument Reference Manual Section 10: Instrument programming
2601B-PULSE-901-01A April 2020 10-57
Removing stale values from the reading buffer cache
The node that acquires the data also stores the data for the reading buffer. To optimize data access,
all nodes can cache data from the node that stores the reading buffer data.
When you run Lua code remotely, it can cause reading buffer data that is held in the cache to
become stale. If the values in the reading buffer change while the Lua code runs remotely, another
node can hold stale values. Use the clearcache() command to clear the cache. For additional
detail on the reading buffer cache commands, see bufferVar.cachemode (on page 11-19) and
bufferVar.clearcache() (on page 11-22).
The following example code demonstrates how stale values occur and how to use the clearcache()
command to clear the cache on node 2, which is part of group 7.
-- Create a reading buffer on a node in a remote group.
node[2].tsplink.group = 7
node[2].execute("rbremote = smua.makebuffer(20)" ..
"smua.measure.count = 20 " ..
"smua.measure.v(rbremote)")
-- Create a variable on the local node to
-- access the reading buffer.
rblocal = node[2].getglobal("rbremote")
-- Access data from the reading buffer.
print(rblocal[1])
-- Run code on the remote node that updates the reading buffer.
node[2].execute("smua.measure.v(rbremote)")
-- Use the clearcache command if the reading buffer contains cached data.
rblocal.clearcache()
-- If you do not use the clearcache command, the data buffer
-- values will never update. Every time the print command is
-- issued after the first print command, the same data buffer
-- values will print.
print(rblocal[1])
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