I have a 24v 4-20ma Pressure transmitter connected to A3 but the raw measurements even with zero pressure fluctuate.
What is the best way of connecting this for maximum accuracy and stable numbers.
In ESPHome, this is mu code and the Zero Pressure fluctuates by 100
- platform: adc
pin: 6
raw: true
name: "F16 A3 Current"
update_interval: 5s
unit_of_measurement: mA
attenuation: 0db
samples: 100
sampling_mode: avg
sampling_mode: max try to test by this option.
(08-09-2025, 04:29 AM)admin Wrote: [ -> ]sampling_mode: max try to test by this option.
Unfortunately it doesnt work.
The raw values when 0 pressure can range from 2352 to 2556. Middle range static pressure is similar in variation. 3320 to 3440
I am using shielded cable and using the GND from the unit.
The Sensor is a 24V 4-20mA Pressure Transmitter
Hookup:
+24V--------- +Sensor- -------------A3 input
I there a way I can test the ADC stability?
Do you have another analog sensor? or you can test with a static voltage, such as 3.3v. see the value whether stable showed in webpage.
(08-14-2025, 05:14 AM)admin Wrote: [ -> ]Do you have another analog sensor? or you can test with a static voltage, such as 3.3v. see the value whether stable showed in webpage.
Unfortunately I do not. Theyre all pulsed outputs.
Can I hook up a potentiometer to it? 150 ohm across 3.3v and gnd and the wiper into A3 and then check the stability mid range?
sure, you can find a 3.3v point on PCB, use a cable short connect to A3 , see the data whether will stable.
Im having trouble with a pressure transmitter (4-20mA @24v).
It suffers from decay over a period of time. I asked chatGPT to help out and it says that its caused by “the repeated conversions act like a little pump that drags the node down, so the reported value “decays” over minutes/hours”
Ok so I get it (sort of) so I installed a 250ohm shunt resistor between the ADC IP (the op of the sensor) and GND. It also suggests installing a 0.1uF cap in the same spot (in parallel w the shunt resistor)
1: this stabilizes the measurement for approx 2-3hrs and then the decay resumes. Would a lower resistsor give me a more reliable time duration???
2: Not sure about the 0.1uF cap except for reducing line noise…
Is this correct and can someone point me to a picture somewhere in the internet that shows a cct diagram.
Thanks
i have isolated the code and its not to do with the code, its the electronics side.
So is the cct below a better way of fixing the issue????