Problem with reading voltage information using DS2450

[Lebelin]

I make a data logger to have information on the electric situation on an amateur television relay.The display use an OSD circuit and i wish to use a DS2450 to obtain infos on the batteries charge current.Other 1wire circuits are already used without trouble.(time,temperature)
I encountered a problem in reading the voltage informations with DS2450.
When i select the port to be used with the "select mask" the last one is alway wrong. I explain, i select channels C and D to read voltage, the value D is perfect but the value C is wrong (about 5% more).If i select B,C and D then C and D are correct but B has the same error problem. I tryed in changing the"read out" control without résults.
Somebody have an idea how to resolve the matter as i need 2 channels for reading Volts and Amp and the 2 others have to be used as alarm to switch off the relay if current is below the thresholds.??
Thanks for the help

 

[IanP]

Re: Problem with DS2450

Could you try to operate (initialize, select, ... read) one channel at a time?
Although data sheet suggests that you can select/read all channels at one go but I would try single channel operation, then again, master reset, slave presence , next channel, and again ..
Even if the whole sequence is performed once per second for On-SCreen display operations I think it is fast enough.
Other suggestion would be to increase all times, for example Trstl should be between 460µs and ininity, make it ≈1ms .. an so on ..

 

[Lebelin]

Re: Problem with DS2450

Thanks for the suggestion.I'll try and revert.

 

[Lebelin]

Re: Problem with DS2450

with only one channel (D) i have exactly the same problem i.e the error. C3 instead of AC . i make my chek on a LCD in hex.
I continu my investigations to understand the problem and i will mail to Dallas to obtain an info.
Thanks again for help