BM869s Maximum Logging Rate

[IanB]

I started doing some tests with the BM869s data link cable, curious about how fast data can be retrieved over the cable.

Here is the result of my first preliminary test where I just tried to retrieve data as fast as possible. I got a sample interval of about 200 ms. The data were mostly smooth and without jitter, except there was one data point shifted with the wrong time stamp. I don't know the cause yet, it may have been the fault of the logging PC. I got two errors like this in 100 seconds of data.

It is probably conservative to retrieve data on a 250 millisecond clock tick. More experiments are needed.

Code: [Select]

time Voltage
0 8.8
0.215 8.6058
0.399 8.4352
0.591 8.2804
0.799 8.1385
0.991 8.0081
1.175 7.8871
1.391 7.7745
1.575 7.6694
1.767 7.5706
1.975 7.4778
2.167 7.3902
2.36 7.3067
2.567 7.2265
2.751 7.1504
2.968 7.0764
3.152 7.0048
3.343 6.9364
3.65 6.8701
3.744 6.8055
3.928 6.7428
4.144 6.6817
4.336 6.6224
4.519 6.5647
4.727 6.5084
4.919 6.4527

[joeqsmith]

It's hard for me to think of an error every 250 reads as being good enough.   Maybe one out of a million or billion. 

What's the error rate when using their software?

[IanB]

I will do a similar test with the Brymen software.

Since the value comes from the DMM and the time stamp comes from my code, and since the value is apparently correct while the time stamp is shifted, it may be the problem lies with the generation of the time stamp. I will investigate further. My test app is only very crudely constructed at present. I'm just experimenting.