POSITAL offer several new encoders that support the ongoing demand for MODBUS RTU. 

For example, the POSITAL UCD-M200B-1516-HFSS-PRM.

Modbus RTU is an RS485 serial Industrial communications protocol, that came about in the early 1980’s. 

MODBUS RTU Hollow Shaft Encoder
MODBUS RTU Hollow Shaft Encoder
MODBUS RTU Solid Shaft Encoder
MODBUS RTU Solid Shaft Encoder


In those days' some PCs running early SCADA software used serial comms. 

Modbus RTU was by far the favourite protocol and became well known, easily understood and supported.   

The MODBUS RTU development patents have long since expired, allowing developers to utilise the technology royalty free, making Modbus RTU a cost-effective option when choosing an absolute encoder. 

Most industrial automation manufacturers have developed their latest controllers around an Ethernet based communication protocol. 

POSITAL have been at the cutting edge with their absolute encoders supporting all modern protocols such as EtherCAT, Ethernet/IP, Modbus TCP/IP and Profinet. 


However, there are still many process and industrial controllers in Australia using Modbus RTU.  

Simple, or entry level controllers are available with optional hardware to support Ethernet communications. Unfortunately, this is not always a practical or cost-effective solution, and a serial port is the logical option. The same applies to peripheral or slave devices. 

The trend is for encoder manufactures to discontinue their range of MODBUS RTU encoders. 

POSITAL is bucking this trend, continuing to support the MODBUS RTU protocol. 

MODBUS RTU encoders are available from POSITAL with either a 36mm or 58mm diameter housing, with various form factor options such as hollow or solid shaft, axial or radial, connector or fitted cable. 

For further information contact PCA Encoders


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15 October 2021