TEDS hardware and the Dallas One Wire Serial Number

[calspan]

I have a substantial number of sensors that use a pre-teds ID system that consists of a Dallas/Maxim DS2401 serial number chip to uniquely identify sensors.  Could the NI TEDS interface SCXI-1341T be used (with the SCXI1520) the simply read the Dallas serial numbers?  It does not seem like the 64bit chip serial number is included in the TEDS:BitStream.  The hardware interface to the sensor would be TEDS Class 2 compatible.   I have used a serial based reader called by the Dallas TMEX before but it limits me to the one channel.

  

[Paul_C.]

Hi Calspan,

The SCXI-1341T is designed for use with IEEE-P1451.4 Class 2 TEDS sensors; therefore, I'm not sure on how compatible it will be with your older pre-teds sensors.  Do you have the Dallas Semiconductor DS9097U-S09 Universal 1-Wire COM Port Adapter?  If so, here is a good library of vi's that you may be able to use to communicate to the sensor.  Also, here is a good article about reading and writing teds with our LabVIEW PDA module.  Although not as applicable, it has some good information about the one-wire protocol used by your sensors.  I also found another example designed for another 1-wire sensor that you may be able to use.  It uses the TMEX dlls.  It can be found here.  Another great article about sensor calibration with TEDS can be found here.

I hope this helps,
Paul C.

[calspan]

Thanks Paul,

For a different application I am using the Dallas serial interface but the objective of this request is to automatically link the transducer serial number to a physical channel.   If the TEDS terminal board could be queried at the Dallas driver level, the I would have a one-to-one channel association to the serial number device.   If the serial number devices (DS2401) are all connected to a single one-wire adapter I have no way of knowing what device is connected to a channel.

Andy

[Paul_C.]

Hi Andy,

If you can read in the serial number from the device using the 1314T, you would be able to uniquely identify different sensors by their channel using the TEDs serial number information.  I'm not sure exactly if this is possible.  You might try contacting Dallas/Maxim to see if there is a way to get the serial number into the TEDs bit stream. Once you can get the serial information you can use Measurement and Automation Explorer (MAX) to read that serial number information and assign it to a channel.  There is also the TEDS palette in LabVIEW so you can do the same thing programmatically.  If you need the TEDs library, the download can be found here.  In addition, here is a good article for configuring TEDs sensors in MAX and LabVIEW.

I hope this helps,
Paul C