Please Help With Final Project

[KochTech]

Hello,

I am trying to get a Yokogawa Hart pressure Transmitter and a Rosemount Temp Transmitter to read on a 1769-IF4 module on an L33ERM CompactLogix. The displays on the transmitters do not energize, and the values on the card show the cards code for "Undervalue".

I programmed the transmitters/sensors to scale 4-20ma within the desired process values.

I put a 250 ohm resistor in series on each side of polarity on different test. No difference in value.

I know these cards aren't meant to support Hart communication, but has anyone found a unique way to get these to connect?

Thanks

 

[Mickey]

You don't need the 250 ohm resistor, the module provides the load.

See pdf's for wiring options and input load impedance
How do you have it wired?

 

[KochTech]

The Hart protocol transmitters have a low pass capacitor that require the 250 ohms of resistance. The 1769-IF8H cards do, yes, but not the one I have.
"V/I 0 - " to - Transmitter terminal and "I in 0+" to + Transmitter terminal.

 

[danw]

Where is the 24Vdc power supply coming from that powers the field transmitters?

see Mickey's 2nd attachment, top drawing showing DC power supply and 2 wire transmitter wiring.
His first attachment confirms his statement that the module provides 250 Ohms input resistance under 'input impendance'.

 

[KochTech]

I powered the transmitters, first, off of the 24v supplied by the card. Then I tried powering it from a 24v Sola dc power supply after I toggled the power supply switch on the IF4 card to "external power source". Made no difference

 

[JesperMP]

If you use the transmitter as a 4-20mA transmitter with no need for the Hart protocol, then you can use any 4-20mA input card with no special circuitry needed.
The Hart protocol is a frequency modulation on top of the 4-20mA signal.

The displays on the transmitters do not energize,

Pretty much tells you that you don't have 24V supply to the transmitters.

I programmed the transmitters/sensors to scale 4-20ma within the desired process values.

How did you do that without a functioning display ?

Measure if you have 24V supply to the transmitter.
If you can confirm you have 24V supply to the transmitter, then measure with a regular DC ammeter. You should get a signal within 4-20mA. If you get a working mA signal or not will tell you if the problem is with the transmitter or the PLC.

Inform the exact type no's of the transmitters.

 

[JesperMP]

I powered the transmitters, first, off of the 24v supplied by the card. Then I tried powering it from a 24v Sola dc power supply after I toggled the power supply switch on the IF4 card to "external power source". Made no difference

Make a small sketch of your connection diagram, with and without the external power supply.
Did you also connect the ground from the external power supply ?
Try to remove the PLC and connect directly to the transmitters, then measure with an ammeter from output on the transmitter to ground on the power supply.

 

[KochTech]

If you use the transmitter as a 4-20mA transmitter with no need for the Hart protocol, then you can use any 4-20mA input card with no special circuitry needed.
The Hart protocol is a frequency modulation on top of the 4-20mA signal.


Pretty much tells you that you don't have 24V supply to the transmitters.


How did you do that without a functioning display ?

Measure if you have 24V supply to the transmitter.
If you can confirm you have 24V supply to the transmitter, then measure with a regular DC ammeter. You should get a signal within 4-20mA. If you get a working mA signal or not will tell you if the problem is with the transmitter or the PLC.

Inform the exact type no's of the transmitters.

I used a Trex (Hart Communicator) with Loop Power function.

Hello,

I am trying to get a Yokogawa Hart pressure Transmitter and a Rosemount Temp Transmitter to read on a 1769-IF4 module on an L33ERM CompactLogix. The displays on the transmitters do not energize, and the values on the card show the cards code for "Undervalue".

I programmed the transmitters/sensors to scale 4-20ma within the desired process values.

I put a 250 ohm resistor in series on each side of polarity on different test. No difference in value.

I know these cards aren't meant to support Hart communication, but has anyone found a unique way to get these to connect?

Thanks

Figured it out.

+ 24V (Sola) to Transmitter +
- 24 V (Sola) to 1769-IF4 V/I in 0 -
Anlg Com jumpered to V/I in 0-

 

[TWS]

"- 24 V (Sola) to 1769-IF4 V/I in 0 -" Should be - 24 V (Sola) to 1769-IF4 V/I in 0 +

 

[widelto]

@KochTech: you can use the 250 ohm resistor at 4-20 mA input, you will be able to measure voltage across the resistor from1 to 5 volts. If voltage is out of this range something is wrong. And you have to check that your wiring is in accordance with the figure sent by Mickey.

 

[JesperMP]

He figured it out. My guess, he had wired the power supply wrong. The analog PLC card needs external power supply.