I would like to use the factory steering sensor on the fendt 900. The output voltage is from 4v to 8v. About 6v straight ahead. Can I connect it directly to ADS? Is this voltage too high?
You can map the arduino to use any range. But beware, some of us have had problems with ecu’s on tractors when we tried to integrate with existing sensors. Virtually all problems will relate to having diferent ground potential.
…also be certain that the sensor is actually using voltage as the reading. Fendt do use 4-20ma sensors for various operations. These are more difficult to hack into without messing things up.
Yes, the sensor is of the 4 … 20mA current type, so you probably can’t connect to it.
Isn’t the referred solution assuming that the 4 - 20 mA signal is only for one input, the A1 for Arduino in that example.
I assume baraki wants to maintain the sensor reading for the tractor too. A series resistor and differential measurement over the series resistor might keep the tractor working but it might also trigger a fault. Don’t know how big a series resistor would this tractor accept and if it gives high enough voltage to read. Might need a differential amplifier first before the ADC.
Yes. I think to maintain the original destination for the signal, a very low resistance would be needed and then considerable amplification of the difference. How accurate the resulting output would be I don’t know.
TBF I would just add a Landrover sensor and have total freedom to set it up as I wished.
In the service manual they write that the voltage can be read with a meter.
When I measure the sensor with a sensor connected to the tractor installation, I can read stable voltage changes without using a resistor. So maybe the ECU of the tractor is a resistor and just read the voltage?
The question is whether the 4-8v range is suitable for ADS?
Of course, I agree that it would be best to give a second sensor to AG, but they do not want to unscrew the cap screws on the left steering knuckle and the lever system in this tractor with shock absorption on the multichannel is not easy to do …
EDIT: Alan is correct. I had thought an op amp follower circuit might work, since the tractor computer is applying a resistance load to the signal so it can measure the current. However, I don’t believe that can work.
The voltage may not be particularly proportional to the angle. The whole point of 4-20ma is that it is current NOT voltage dependant and therefore immune to cable resistance losses and supply voltage variances etc.
No. See ADS1115 datasheet:
On PCBv2, the power supply of the ADS1115 is 5V (VDD). So the maximum allowed voltage on the input is 5+0.3=5.3V.
Even if you supply the ADS1115 with maximum allowed voltage of 7V, the maximum allowed voltage on the input is 7.3V. So not enought for your 8V.
Prabably with a 4 - 20mA range : the ECU input probably use an precision resistor. But if you don’t have the schematics of the ECU inputs it’s hard to determe if you can isert an other resistor in the circuit without disturbing the ECU.
I also agree with @Alan.Webb about the voltage.
There are 4-20ma signal duplicators. 1 input 4-20ma >> 2 output 4-20ma
Could it work to read the mA sensor with the ads in differential mode? You’d probably need an isolated power supply for the ads/Arduino
So I would need a duplicator and a 4-20 loop converter. The problem is only with the quick availability of a duplicator that would have the appropriate parameters.