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+--- Thread: Read with Wait function (/showthread.php?tid=2139)
Read with Wait function - Thomas - 02.07.2019
Hello
I'm looking for a function which sends read request to KNX bus and waits for the result. The reason is I have two inputs which I need to be sure their values are actual.
This works but it's ugly because I don't check if the readings of both values were successful:
grp.read('6/4/28')
grp.read('6/4/45')
os.sleep(5)
val_a=grp.getvalue('6/4/28')
val_b=grp.getvalue('6/4/45')
Is there such
err,val_a=grp.readAndWait('6/4/28')
?
RE: Read with Wait function - admin - 03.07.2019
Use this function:
Code:
function readresponse(alias, timeout)
local obj, lb, ts, tu, delta, value
obj = grp.find(alias)
if not obj then
return nil, 'object not found'
end
timeout = timeout or 3
lb = require('localbus').new(timeout / 10)
lb:sethandler('groupresponse', function(event)
if event.dst == obj.address then
value = busdatatype.decode(event.datahex, obj.datatype)
end
end)
grp.read(obj.address)
ts, tu = os.microtime()
repeat
lb:step()
delta = os.udifftime(ts, tu)
until value ~= nil or delta >= timeout
if value ~= nil then
return value
else
return nil, 'timeout'
end
end
res, err = readresponse('0/0/3')
log(res, err)RE: Read with Wait function - Thomas - 03.07.2019
Excellent as usual Admin. Thank you.
But does lb:step() do yield? Isn't the cycle utilising the CPU to 100%?
RE: Read with Wait function - admin - 03.07.2019
It returns once a single local bus message has been received or timeout happens. Script does not consume CPU while waiting.
RE: Read with Wait function - benanderson_475 - 19.07.2019
Is it possible for the timeout to re-trigger and over ride the last timeout every time the function i called? i am having a few instances running at the same time
RE: Read with Wait function - admin - 23.07.2019
Do you mean that you want to send several read requests at once and then return once all responses are received or timeout happens?