from the Instrumentation department...
Communication between a HART transmitter using DRUCK DPI 610 24 voltage power source
Communications systems and equipment. topic
Posted by Sakthi venkatesh on 21 December, 2013 - 6:15 am
I want to use 24 voltage from DRUCK DPI 610 as a power source to calibrate HART transmitters.

If I use DC power supply I need to use 250 ohms so that the Hart signals wont get filtered by Low pass filter inside the DC power supply.

How ever i want to use 24 volt from DRUCK DPI 610, here the 250 ohms didn't help. The circuits inside Druck may be different from DC power supply, Instead of resister what can i use?

I want solution please
Thank in advance

Posted by jay on 21 December, 2013 - 11:02 am
Hello there.

I have not used the druck you are talking about, but i looked it up. the 4-20ma function is used for simulation only, not to power up your pressure transmitter. use your druck for your pressure and what i do a lot is take 3 9v battery and push them in series. solder some wire to them with a 250ohm in series and hook it up and you should talk HART just fine. I do this in the field to establish if a transmitter has lost its ability to talk HART.

well good luck

Posted by David on 21 December, 2013 - 3:27 pm
We must have found different manuals on the web. The manual I found for the Druck DPI 610 (User manual - K0415) shows that the Druck sources a pressure, powers a loop powered transmitter, and reads and displays the 4-20mA loop current.

The wiring for powering the loop (current sourcing) from the Druck is shown on page 25 (paper).

The Druck is NOT a HART master. It cannot issue HART commands to change the range or to trim the 4-20mA output. It is HART deaf and dumb.

It appears entirely possible to use the Druck along with a HART communicator or a PC running a HART configuration program like PDM or Pactware with the appropriate DD/DTM/EDD file to do calibration checks on transmitters.

To do so, you'd probably have to put 250 ohms in series in the loop and connect the HART modem/communicator leads directly across the resistor.

I, too, use three 9 volt batteries as a floating power supply. It's a great tool to confirm whether a 'dead' transmitter is still functional or whether there's a problem (open circuit, failed power supply) in the loop.

Posted by jay on 23 December, 2013 - 10:57 am
very good. i am just have never worked with or know the capabilities of the the test equipment.

Try it both ways would love to hear if it has built in loop resistance or not. If I were creating it I would think I would put it in.

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