1. Getting started
1.1. Rheonics SRV, SRD, DVP or DVM w/ Firmware V03.20/0 or higher
1.2. Allen Bradley Micro820 2080-LC20-20QBB
1.3. Rockwell Automation CCW Version 12.00.00 (includes RSLinx Classic Lite 4.11.00 CPR 9
1.4. Windows 10 64 bit
1.5. 500 Ω Terminal resistance
2. PLC Wiring
2.1. Connect SMET 4-20 mA output channels to the PLC analog inputs by using a resistance connected to the analog input’s channels (For micro820 those go from I0 to I03, the resistance is needed because the PLC only read voltage from 0 to 10V). For this example, we are using an impedance of 500Ω.
Figure 1. Analog inputs in Micro820
2.2. Follow this table to fix the correct values for 4095 point available for the analog input and the correlation with the resistance.
Table 1. Voltage-Current Correlation
2.3. Wire the channels from the SMET according to the article(https://support.rheonics.com/support/solutions/articles/81000297457-connecting-4-20-ma-outputs). All the channels from the SMET are already internally powered so no additional power supply is need it
Figure 2. Analog output channels from SMET
3 Rheonics control panel settings
3.1. 4-20mA Settings in “Service” Tab
This box allows to read and set the upper and lower limits for each of the 4-20 mA measurement channels and also to select which parameter is assigned to each channel.
Figure 3. 4-20mA settings box
3.2. Open the dropdown list and select the parameter to measure. The parameters available are:
- Kinematic Viscosity
- Calculated Viscosity
- Calculated Density
Figure 4. Selecting parameter in dropdown list
3.3. To change the upper and lower limits, follow the next steps:
2.3.1. Enter the lower limit on the box labeled “4 mA”.
2.3.2. Write the upper limit on the box labeled “20 mA”.
2.3.3. Click the “Update” button to send the new values to the SME. If the write operation succeeds, the “Write” button will turn green for a few seconds. Otherwise, will turn red and the boxes will go back to the previous values.
Figure 5. Updated limit
4. PLC setup
This section explains how to navigate in the CCW software to configure the correct analog inputs settings. Rheonics provides a premade .CCWARC as a basic program for the analog input connection.
- Open the Connected Component Workbench (CCW) Application
Figure 6. Connected Components Workbench start
2. Once in the CCW environment go to the “file” tab and select Import project.
Figure 7. Import Project in CCW
3. Choose the file named “RheonicsSRV_micro820_analoginput.ccwarc” . All the project configurations will be displayed on the screen.
Figure 8. Selecting ccwarc file
4. The Analog input settings can be verified by selecting the Global Variable option.
Figure 9. Checking analog inputs on Micro820.
5. Ladder program for analog inputs, limits are set with the same values used in the RCP software.
Figure 10. Ladder program for analog inputs.
6. Comparison between output values from PLC and RCP. These values can be improved by calibrating in “Service” tab
Figure 11. Micro820 vs RCP comparison in readings