What products are involved?

This article’s goal is to showcase how measurements from Rheonics inline process viscometer (SRV) and inline process density meter (SRD) can be displayed with Explosion-Proof displays in an EX area.

What is an explosion-proof display?

Ex enclosures with explosion-proof displays are used in industries like oil and gas, chemical processing, and mining, where hazardous environments are prevalent. These enclosures provide secure, explosion-proof housing for equipment.

The explosion-proof display equipped with Modbus communication, allows operators to safely monitor equipment status, process variables, and other critical data directly from the enclosure without the need to open it. 

1. Key suppliers of  Explosion-Proof displays and how to integrate Rheonics Type-SR sensors

1.1. Precision Digital

Precision Digital Corporation produces an EX-approved explosion-proof Modbus display/scanner, designed for industrial processes.

Figure 1. ProtEX-MS2- Explosion proof Modbus scanner[1]

1.1.1. Modbus scanner-Master mode 

In Master mode, the scanner can poll up to 16 Modbus registers from 16 different devices, acting as the network master to retrieve process variables (PVs) from Modbus slave devices for display or use in mathematical functions.

Configured as a master, the PD6830X (Smart display) enables visualization of viscosity, density, and temperature from one to four sensors. The schematic below shows 4 sensors in 4 separate tanks, whose measurements are displayed on a single display placed in the EX area.

Figure 2. Tank indicator for 4 Rheonics Ex sensors. 

1.1.2. Modbus Scanner-Snooper mode 

When the Modbus scanner is set to Snooper mode the display monitors Modbus traffic and identifies specific registers being polled by a Master device from a designated Slave device. It processes the data retrieved, supporting up to 16 process variables (PVs) from as many as 16 devices. If a Master device polls multiple registers with a single command, only the first returned value will be processed.

1.1.3. How to map the Modbus variables in PD6830X?

Mapping variables can be done from the Scanview Ex software “mode/PV setup” page, the display processes and displays data read from Modbus RTU slave devices. Up to 16 process variables (PVs) from up to 16 slave devices. Each PV is programmed individually.

Figure 3. Modbus mapping on PD6830X.

The PD6830 UI is intuitive and parameters can be configured easily. Figure 4 below shows how to set the proper address on the 16 parameters available for monitoring.

Figure 4. Parameter setting based on the SME registers.

Variables can be monitored on the main screen and units edited as needed. Figure 5 below shows how we can add the viscosity, density, and temperature that can be read online with the ScanView software.

Figure 5. PD6830X Monitor editor.

2. References: 

[1] https://www.predig.com/pd6830x