Vincenturion
Member
Good day to you all,
First of all, I'm new to this forum as I'm seeking your help from experienced programmers and electrotechnicians (for both professional or hobby)
I'm facing a challenge, I work on a merchant vessel and a while ago some electrician has installed a 0-10VDC pressure transmitter and a control unit which only works with a 4-20mA sensor.
The Uopen (open contact voltage) or the PLC is 22VDC, the pressure transmitter has a separate power supply set to 24VDC. To change the signal from 0-10VDC to 4-20mA a converter is installed (consisting of op amps I assume?).
This converter gets power from the same 24VDC supply as the pressure transmitter, the + connection input is coming from the 0-10VDC signal wire from the transmitter and the - signal input comes from the - of the 24VDC power supply.
On the converter module there are 2 potmeters, 'zero' and 'gain'. The 4-20mA connection open contact voltage is 10VDC. When I measure mA between the output signal contacts I can properly adjust zero to 4mA and see signal increase as the input voltage increases. However, here is my problem, when I connect the output of this module to the input of the control PLC I get a steady current of 22mA that barely changes while changing the zero and gain of the converter, and also the voltage over the input contacts has decreased to 15VDC.
Now I know the use of mA signal can have two main purposes; receiving a signal, or sending a signal to e.g. an actuator. I suspect that this converter module is designed for sending control signals instead of particularly transforming a V signal to mA signal for receiving a sensor value. I also know that transforming mA signal to V is relatively easy as installing a resistor of 250 Ohms for 0-5V (from 0-20mA) and 500 Ohms for 0-10V will do the trick. However, I have found that the other way around is not that simple. I lack the knowledge and experience in solving this matter myself, especially with the limited access to the internet while at sea.
Right now I'm seeing a few options causing this problem:
- System is wrongfully connected
- Converter is malfunctioning
- PLC is malfunctioning
- Converter is not designed for this purpose.
I really appreciate your thoughts and ideas on this, I'm always eager to learn so this is a good opportunity for me to improve my knowledge on this matter.
First of all, I'm new to this forum as I'm seeking your help from experienced programmers and electrotechnicians (for both professional or hobby)
I'm facing a challenge, I work on a merchant vessel and a while ago some electrician has installed a 0-10VDC pressure transmitter and a control unit which only works with a 4-20mA sensor.
The Uopen (open contact voltage) or the PLC is 22VDC, the pressure transmitter has a separate power supply set to 24VDC. To change the signal from 0-10VDC to 4-20mA a converter is installed (consisting of op amps I assume?).
This converter gets power from the same 24VDC supply as the pressure transmitter, the + connection input is coming from the 0-10VDC signal wire from the transmitter and the - signal input comes from the - of the 24VDC power supply.
On the converter module there are 2 potmeters, 'zero' and 'gain'. The 4-20mA connection open contact voltage is 10VDC. When I measure mA between the output signal contacts I can properly adjust zero to 4mA and see signal increase as the input voltage increases. However, here is my problem, when I connect the output of this module to the input of the control PLC I get a steady current of 22mA that barely changes while changing the zero and gain of the converter, and also the voltage over the input contacts has decreased to 15VDC.
Now I know the use of mA signal can have two main purposes; receiving a signal, or sending a signal to e.g. an actuator. I suspect that this converter module is designed for sending control signals instead of particularly transforming a V signal to mA signal for receiving a sensor value. I also know that transforming mA signal to V is relatively easy as installing a resistor of 250 Ohms for 0-5V (from 0-20mA) and 500 Ohms for 0-10V will do the trick. However, I have found that the other way around is not that simple. I lack the knowledge and experience in solving this matter myself, especially with the limited access to the internet while at sea.
Right now I'm seeing a few options causing this problem:
- System is wrongfully connected
- Converter is malfunctioning
- PLC is malfunctioning
- Converter is not designed for this purpose.
I really appreciate your thoughts and ideas on this, I'm always eager to learn so this is a good opportunity for me to improve my knowledge on this matter.