Mapping Data from an RS-485 PLC Network

Have you ever wondered how to connect your RS485 Modbus variable speed drives to your PLC via Ethernet? This Tech Tip illustrates just how easy it is with a Red Lion Data Plus.

It’s a simple 3 step process!

Step One

Assuming you already have Red Lion’s Crimson 3 programming software (If not that’s ok, it’s free via this link: www.redlion.net/crimson-30). Select the first protocol and device/s (in this example VSD/s) that will link with the Red Lion Data Station Plus via Modbus RTU using the RS485 port.

Step Two

Select the second protocol and device, (in this example an AB PLC) that will communicate with the Red Lion Data Station Plus via the DF1 protocol using the Ethernet port.

Step Three

Create a ‘Gateway Block’ to exchange data between the VSD/s on the Modbus RS-485 network and the Allen Bradley PLC on the Ethernet network. In this example, the data from VSD Modbus registers 400001 and400002 is mapped to N007:0000 and N007:0001 registers in the Allen Bradley PLC. So not only have we now performed a protocol conversion between Modbus and DF1, but we have also Ethernet enabled the RS485VSDs!