The SME can produce HART-compatible signals for any HART communicator, this is accomplished with the 4-20mA analog signal that is on channel 1 from the SME. . For the connection of the modem or communicator with the HART board, a resistor of the value ~250Ω is needed.
1. Analog Output 1: 4-20mA
The HART Communication is supported on an active two-wire 4-to-20mA current loop.
Figure 1. Electrical wiring.
Note: SME 4-20mA outputs are self-powered from SME, so no external power is required to power the 4-20mA channels on the SME.
2. Wiring Diagram
Figure 2. Connection over the network.
3. Establishing the analog limits with the RCP
RCP is one of our main applications, it is primarily used for monitoring and recording the sensor measurements: Viscosity, density, temperature, and pressure. It is also used to configure the sensor electronics, and the various communication protocols available on the Rheonics sensors.
Channel 1 is set to density in SME with a 4-20mA range set to 0 – 1.5g/cc. These limits can be edited but be aware that it sets the primary variable range as well. The primary variable always tracks what is in channel 1
Figure 3. Density parameters in SME.