FBx Communications: Using Both ROCTalk and DNP Simultaneously

As stated in our previous post, FBx Historical Configuration and Log Retrieval Using ROC Protocol for SCADA and IIoT Remote Monitoring, there are some significant changes to the way FBx are set up compared to the older Flobosses.

One of the major changes between Flobosses and the new FBx flow computers is that the FBx meters now use DNP as their primary protocol. In order to stay backwards compatible with existing SCADA systems, Emerson provides an optional ROCTalk Protocol communication for the FBx meters.

This creates a new problem, however: if an installer wanted to connect the FBx to an existing network and poll it using ROC Protocol, they would no longer be able to use the Field Tools because Field Tools requires the DNP Protocol to talk to the device.

This post shows 2 methods to access the same device with multiple protocols.

Solution 1

If there is a second port available installers can connect the FBx unit to a different radio or modem port.

The first port (COM1) can be set up for DNP so that Field Tools can communicate with it:

The second port (COM2) can be set up with ROC Protocol:

Wiring Example for Multiport Radio / Modem:

Solution 2: Multidrop ROC and DNP on the Same Port

In the more likely event that you do not have a second port on the radio or modem and need to share a port, one solution is to multidrop the RS485 from COM1 (DNP) to COM2 (ROC). Then the SCADA system can share the port with the Field Tools application.

Since the ports talk two different protocols, if you are trying to communicate to the ROC Protocol the DNP Protocol on COM1 will ignore it, and visa versa.

COM1 is set up with DNP3 Protocol and RS-485 Serial Mode: