Tags: binary, buses, communication, file, filesquot, individualnbsplog, labview, loops, multiple, own, parallel, programming, quottdm, streaming, system, tasks, various, versus, write
Labview 8.20 - "TDM streaming versus Binary Files"
I have multiple loops/parallel tasks with various communicati
on buses in an RT system which need to write data to its own individual
;log file which is using an Binary format. What kind of benefits will I get
in terms of performance by
using the TDM Streaming? The only benefit I foresee is the consolidati
on of data into an XML type structure and store data into an universal file
versus 4 individual ones.:smileysurprised:
Are TDMS being handled differently in RT for disk IO management? becaus
e each write will take upto 8-9 ms.The goal is to reduce disk IO and improve
Ashm01Message Edited by ashm01 on 10-30-2006 11:46 PM
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- 2 Comments
- Hey Bill,
Is your application in RT? I would appreciate if you have some benchmarks on
this. I am about to convert the binaries to TDMS and was wondering if anyon
e had any favorable performance gains.
Ashm01#1; Sat, 10 May 2008 02:04:00 GMT
- Hi Ashm01,
The TDMS API was developed to facilitate streaming data to disk at high rate
s, while maintaing the same descriptive information you would find in a TDM
file. You might find the following information interesting from an article o
n Developer Zone (<a href="/app/links/?link=
http://zone.ni.com/devzone/cda/tut/p/id/3539" target="_blank">Introduction t
o LabVIEW TDM Streaming VIs</a> ):
Unlike the TDM files, which have a strictly required XML-based header file,
TDMS files have a binary index file with the extension *.TDMS_Index. The TDM
S_Index file provides consolidated information on all the attributes and poi
nters in the bulk data file
, and speeds up access to the data...
I believe you'll find that the TDMS VIs are on par with the regular binary f
ile I/O from a performance standpoint -- plus you get all the benefits that
TDM offers. If you are trying to optimize File I/O on LabVIEW Real-Time in g
eneral, try writing to a fi
le in chunk sizes that are a multiple of 512 bytes and maintaining a 51
2-byte-multiple offset with respect to the beginning of the file. Since
512 bytes is the size of a sector on a hard disk (the basic unit that is re
ad or written from a disk),
you should see some dramatic improvments.
Hope this helps!#2; Sat, 10 May 2008 02:05:00 GMT