Configuring the PM50 as a Numeric Modbus Slave Display

Use Case:

          When you want one or two numeric data points with units shown on a local screen some distance away from the Master/Data host at an economic price point.

General Overview:

          The PM500D models specifically have their main count registers readable and writable by a Modbus master. This means we can take advantage of these registers having access to the display screen to display any Modbus writes coming from the master. (Note: The PM500A models have read only registers, and cannot take advantage of this document)

            The PM50 has three pathways to communicate over Modbus:

• Serial RS485 (stock on unit, uses terminals 7 and 8)
• Modbus TCP/IP over ethernet (requires the PMM000CMENT00000 ethernet module)
• Modbus TCP/IP over Wi-Fi (available stock, but requires a wireless network and susceptible to environmental noise)

Required Materials:

• PM500D0400800F00 or PM500D0301600F00
• Modbus Master with Access to desired data
• RS485 Communications cable or PMM000CMENT00000 ethernet module

Setting up the Screen:

1. Click the gear icon on the top right of the screen
2. Now select the “Home screen” icon at the far right that looks like a landscape painting.
3. Click on Screen Configuration
4. Click “Widget Selection”
5. Choose screen 1
6. Choose a numeric display style
7. Select Counter next (these registers are writable)
8. Leave Counter A selected
9. Now you can set your display units for the screen
10. Apply your changes

Additional Notes:

If you wish to write two values to the unit, follow these same steps for widget 2 and select Counter B instead of A.

If you wish to show one value on a 4.3” display, select and enable the Large numeric Widget in this same menu, the follow the preceding steps selecting Large numeric in the Widget selection window instead of widget 1 or 2

Using RS485:

1. Terminate your A and B wires on terminals 7 and 8 respectively
2. Enter the programming menu (gear icon at the top right)
3. Click on the device menu icon (looks like a computer monitor)
4. Click the red arrow to the right
5. Now click on “Modbus Configuration” followed by RS485 Configuration
6. You can now set your serial parameters like Modbus Communication type, baud rate, parity, and address.
7. Once you’ve set all serial parameters to match your master device, you’re finished configuring communication

Using the Ethernet Module for TCP/IP:

1. Plug in your Ethernet module and plug your ethernet cable into it
2. Enter the programming menu (gear icon at the top right)
3. Click on the device menu icon (looks like a computer monitor with arrows)
4. Click the red arrow to the right
5. Now click on “Modbus Configuration” followed by Ethernet Configuration
6. You can now choose to setup your Ethernet settings for your network such as if it’s a DHCP server or the unit’s IP address, subnet mask, and gateway if not.
7. If you would like to adjust the unit’s Modbus address, enter the RS485 programming menu, skip every option until ‘address’ is presented, then make your change and apply.
8. Once these settings match the network/master’s settings, you’re finished configuring communication.

Using Wi-Fi for TCP/IP:

1. Enter the programming menu (gear icon at the top right)
2. Click on the Network Configuration selection
3. Click Wi-Fi configuration, then enable Wi-Fi
4. Set an admin password if you haven’t already (between 6-10 characters)
5. Choose client mode to pick your network
6. Select whether your network has DHCP enabled or not
7. Enter the SSID of your network followed by the password on the next page
8. Make sure to enable Modbus/TCP over Wi-Fi
9. Apply your changes, you are now finished configuring the PM50 for Wi-Fi communication

Writing to the PM50 from the Master:

            When writing to the PM50 from your master, you want to make sure the master is formatted to exchange 32-bit integers with the PM50. From there, the following registers can be written to:

40001 -> Counter A register

40003 -> Counter B register

            As long as a numeric value is passed between the Master and the PM50 in 32-bit integer format, the PM50 should now display the Master’s write. Your configuration should now be complete.

Disclaimer:

It is the customer's responsibility to review the advice provided herein and its applicability to the system. Red Lion makes no representation about specific knowledge of the customer's system or the specific performance of the system. Red Lion is not responsible for any damage to equipment or connected systems. The use of this document is at your own risk. Red Lion standard product warranty applies.

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