Part 4 of this series discussed the issues and requirements involved in the design of a 2-wire sensor transmitter that accepts inputs from an externally powered sensor/source. In this installment, I’ll expand on the concepts presented in that post and…
The previous three parts of this blog series focused on 2-wire 4-20mA sensor transmitter designs composed completely of analog components. While analog signal conditioning is practical for linear sensors, many sensors have nonlinear outputs that can only…
In part 5 of this blog series , I discussed the construction of an input-isolated 2-wire sensor transmitter. Input-isolated 2-wire transmitters require isolating the sensor power and data signals from the 2-wire loop supply and 2-wire loop return (RTN…
Part 2 of this blog series derived the basic transfer function for a typical 2-wire transmitter, commonly used in industrial control and automation, and explained the currents flowing inside it. It also explained that connecting the transmitter return…
Hello Patrick,
While in theory an idea like that may work, the actual implementation would violate the standards for 2-wire 4-20mA transmitters which require only two wires (Vloop, RTN) in the loop. Take a look at Part 4 which talks about a similar application…
My previous posts discussed the basics of 4-wire sensor transmitters, along with a detailed design of an output-isolated sensor transmitter. Today, I’m discussing power-isolated 4-wire sensor transmitters.
First, let’s review the high-level diagram…
Other Parts Discussed in Post: LM5017 In my last post , I discussed the basic structure of 4-wire sensor transmitters and how they differ from 2-wire and 3-wire sensor transmitters. In this post, I will discuss the construction of a locally powered output…
My previous posts discussed the basics of 4-wire transmitters and showed circuit-level design options for output and power-isolated 4-wire sensor transmitters. In this post, I’ll cover the final isolation configuration for 4-wire sensor transmitters …
Part 1 of this blog series provided an overview of the operation and uses of 2-wire 4-20 mA field sensor transmitters and provided a basic example system. The post also introduced the current transmitter compliance voltage, which when violated prevents…
Part 1:
2-wire 4-20 mA sensor transmitters are very common in industrial control and automation. They are popular because they allow a remote process to be monitored with only two analog signal wires. The two wires carry both the power for the sensor…