DS2438 support

[CAI_Support]

What would be the best name to call those four DS2438 current measurement? 
Each DS2438 has a current measurement register to read in the current value.  What do you like to see that being called in PLC?
 
We have DS2438 chip support code working now, with a lot of changes to 1-wire bus code.  DS2438 has much higher accuracy than DS18B20, so that user can read 0.1 degree change instead of 0.5 degree change in DS18B20.
 
DS2438 has a 10V analog input, overlap in memory location with DS2450 storage space, that means if using DS2438, do not use DS2450 at the same bus. In our test, DS2438 is a lot tolerable to noise than DS2450.
 
We have not implemented the functions to read CCA and DCA registers, or reset them.  We will add those support later, after some beta testing with voltage and current first.

 

[CAI_Support]

I think we will call those current readings as
CA1, CA2, CA3, and CA4.
The current accumulators will be called
CCA1, CCA2, CCA3, CCA4 and
DCA1, DCA2, DCA3, and DCA4
 
the index 1, 2, 3, 4 corresponding to the DS2438 assigned in temperature sensor position MOD by four.  Because the voltage reading will be on aip5, aip6, aip7 and aip8, it would be easier to reduce confusion by assign them to temp sensor 5,6,7,and 8.
 
If anyone is interested in beta testing this version firmware, please send us email.  Your board must have bootloader to be able to load this firmware.

 

[rossw]

I think we will call those current readings as
CA1, CA2, CA3, and CA4.
The current accumulators will be called
CCA1, CCA2, CCA3, CCA4 and
DCA1, DCA2, DCA3, and DCA4
 
the index 1, 2, 3, 4 corresponding to the DS2438 assigned in temperature sensor position MOD by four.  Because the voltage reading will be on aip5, aip6, aip7 and aip8, it would be easier to reduce confusion by assign them to temp sensor 5,6,7,and 8.
 
If anyone is interested in beta testing this version firmware, please send us email.  Your board must have bootloader to be able to load this firmware.

 
I think it is unnecessarily confusing to have the voltages on aip5-8 and the current on 1-4. Suggest you use CA/CCA/DCA5-8 to align with the voltage inputs.

 

[CAI_Support]

Ross, thanks for your feedback on this.
Just to state clear on this, user can assign the DS2438 as temp sensor 1,2,3,4
or 5,6,7,8, the voltage measurement will always go to aip5,6,7,8,  since internal analog input will always be
1,2,3,4
 
With that, do you still think we should assign CA/CCA/DCA to 5-8?  What if user does not use DS18B20, only use four DS2438?

 

[rossw]

Ross, thanks for your feedback on this.
Just to state clear on this, user can assign the DS2438 as temp sensor 1,2,3,4
or 5,6,7,8, the voltage measurement will always go to aip5,6,7,8,  since internal analog input will always be
1,2,3,4
 
With that, do you still think we should assign CA/CCA/DCA to 5-8?  What if user does not use DS18B20, only use four DS2438?

 
I don't like casting things in stone, because they always come back to bite you later!
 
That said, I just think it's asking for trouble to permit different parts of the same device to have totally different index numbers.
I would be "less disinclined" (double-negatives, anyone?!) to always assign the DS2438 as 5-8 even if there are no DS18B20 devices installed.
Yes, that means that you could have a board with only one temperature sensor and that would be T5 (not T1). That situation could happen with 18B20 devices too, if a user wished to.
 
When a user wants to calculate power (watts) and multiplies the voltage (aip5) by the current (ca1), it's going to get someone far more confused than knowing that aip5*ca5 = watts[5]

 

[CAI_Support]

Because assigning temp sensor number is in user gui, WC logic can not force user always assign DS2438 to upper four numbers.  However, we could change our code to have CA/CCA/DCA to use 5,6,7,8, since AIP5,6,7,8 is forced anyway.  Maybe this way, user will be hinted to use T5,6,7,8 for DS2438.
 
DS2438 current measurement is actually a 0.2441mV/LSB voltmeter, with 10bit accuracy and allow both directions. i.e. plus or minus one volt.  By changing different size sense resistors, it can measure the current flowing through that sense resistor. that value is also being stored in the CCA and DCA for charging and discharging based on plus or minus.  One MUST add a RC network to filter possible noise, that filter is simple to add detailed in DS2438 datasheet.

 

[CAI_Support]

We made beta release version 3.02.18 for anyone brave enough to try.  Please send us direct email if you have PLC board with bootloader.  After user testing, we then will release that into production.
 
Once again, any suggestion based on test result is welcome.

 

[CAI_Support]

We have shipped 3.02.18 firmware with DS2438 support in it.
Please see our updated user manual at
http://www.cainetworks.com/documentation/documentation.htm

 

[Efried]

We have shipped 3.02.18 firmware with DS2438 support in it.
Please see our updated user manual at
http://www.cainetworks.com/documentation/documentation.htm

 
 
ok, would be  great learning more about the timeline for new functionalities, is there a approved wish list? 
 
many thanks

 

[rossw]

ok, would be  great learning more about the timeline for new functionalities, is there a approved wish list? 

 
You submit wishes and justifications for them, along with hints of how they might be used, by whom etc.
If they're useful enough, well enough described, practical to implement, then given time they appear
 
(At least, that's been my experience!)

 

[Efried]

You submit wishes and justifications for them, along with hints of how they might be used, by whom etc.
If they're useful enough, well enough described, practical to implement, then given time they appear
 
(At least, that's been my experience!)

 
did the possibility to use comments (which are stripped automatically and not stored in the WC) already appear? ;-)

 

[CAI_Support]

Efried,
 
Keep asking you may get it.....we just tested a update that allow comments to be filtered out in pasted PLC code on web gui.
We selected # as the indicator for anything follow that character is comment.
Also any line started with # will be treated as blank line.
comment is not saved in WebControl.  Once pasted into web gui PLC window and saved, next time power on, the command will be gone, only PLC logic code saved into EEPROM.
 
That can be downloaded next Monday from our web site.  Anyone has interest please let us know.
 
Thanks.

 

[CAI_Support]

We have released update firmware with DS2438 support, I2C support, and PLC program comment removal features for free download on this forum. Please do provide your feedback to us for any question you may have during using these features.

 

[LarrylLix]

Sorry to drag this old thread up again but it looks like the right place.
 
       What is the difference between the DS2438 and the DS2438Z ?
 
The spec sheets seem to use them interchangeably and I can't identify a difference.

 

[CAI_Support]

"Z" is probably having something to do with packaging, no difference in commands or function.