1-Wire Energy Management Projects

Home Telemetry and Control Systems to Monitor and Reduce Energy Costs

  DS2450 Board

The Maxim 1-Wire DS2450 chip is a 4 Channel Analog to Digital converter (ADC). Some of the features of the device include:

  • User programmable input range of 2.56V or 5.12V with resolution of 1 to 16 bits!
  • Unique, factory-lasered and tested 64-bit registration number. No two part registration numbers are alike!
  • 5V single supply operation
  • Channels not used as analog input can serve as open drain digital outputs for closed-loop control (this is explained below)
  • Operating temperature range of -40F to +185F

Pictured above is the DS2450 board (prototype) with four I/O boards plugged-in. The first board (position A) is a straight pass-through board which supports analog input voltage. I have a number of boards in work to support analog input:

  • Solar Intensity board
  • Pressure Sensor (to determine when your air filter needs changing)
  • Humidity Sensor

The second board (position B) is a Output board using a Solid State Relay chip, Panasonic AQH3223. Above, under Features, the third bullet talks about "open drain digital output". So technically the DS2450 chip can be an output board, switching things on and off or a A/D Converter input board (or a combination of both)

The third board (position C) is a mechanical relay output board and the forth board (position D) is a test board.

Pictured above is the DS2450 board with an RJ11 jack instead of the screw terminal block. RJ11 uses a standard phone jack (but NOT standard phone cable) for connecting boards together.

Other features of this DS2450 Board include:

  • 24V AC input via screw terminal block. The power is then routed up to the IO Boards attached.
  • Secondary 5V DC supply voltage capability
  • Power status LED positions (upper right of board)
  • Voltage stabilizing capacitor position (not required)
  • Pull-up resistor position (not required)
  • Clamping diode (not required)

Again, this board is still a prototype. When (and if) we go to production we will add the capability for DIN Rail mounting and board inter-connection on the DIN Rail (end-to-end). 

The inter-connect would support:

  • 5V DC power
  • Ground
  • Four (4), yes 4, 1-Wire data lines, pick one
  • 24 V AC power distribution
  • Alternate 5V DC power
  • Alternate DC voltage (like 12V DC or 16V DC, whatever your design needs)

Below is a picture of the inter-connect capability on a DIN Rail. (this will eliminate lots of wiring headaches!) 

And finally a little more on a no-so-well understood capability of this board. Back at the top we mentioned that channels not used as analog input can serve as open drain digital outputs for closed-loop control .

Anybody wondering what exactly that means?

It means that the DS2450 can be programmed to monitor a channel for a specific voltage (say on Channel A) and if the voltage goes above a pre-programmed 4 VDC, turn on Channel D (digital output). If the Voltage drops below 4 VDC, turn off Channel D.

The DS2450 can then run totally on it's own, probably powered by a 9V battery. It would run for a year or more on the battery and you could even put in another test on Channel B to monitor the 9V battery and turn on an LED when the battery needs changing.

I have plans for a project like this in the future near future!

 

Wire Length

The other advantage of these devices is the distance you can run the wires (phone cord) from the controller.

Sources on the internet claim 1-Wire devices support distances of thousands of feet. I've not tested that but so far my shorter distance tests have been successful.

In my project I plan on running about a dozen temperature sensors with wire lengths of about 300 total feet. (This is not as easy as it sounds but we'll discuss that in my "Timeline" articles)