Customized Modbus RTU protocol absolute encoder

Company B is an American company specializing in transformer monitoring systems. It is planned to use our company’s CAX60 series multi-turn absolute encoder for position monitoring. The encoder adopts the international standard Modbus RTU protocol, protection grade IP67, excellent performance, suitable for various harsh working environments.

Since the output data length of the communication protocol is 16 bits, there is no problem with data acquisition for most controllers with 16-bit register; unfortunately, the customer’s controller has built-in 8-bit register, so it is reading the code encountered difficulties when importing data. For this reason, we have modified the encoder program to meet the specific needs of customer. First, it is compatible with standard data read instructions; second, it is divided into two data read instructions. The first communication instruction stores the first half of the data in register 1, and the second instruction stores the second half of the data. Stored in register 2. Then the controller will combine the data of the two registers to get the correct and complete data.

Register read – works as before. Request:  01 04 00 01 00 02 CRC  Reply: 01 04 04 XX XX XX XX CRC
Register1 read.  Request: 01 04 00 01 00 01 CRC Reply: 01 04 02 XX XX CRC

Register2 read.  Request: 01 04 00 02 00 01 CRC Reply: 01 04 02 XX XX CRC

Not only that, according to the customer’s installation requirement, we also customized the encoder shaft to φ4.76×13.84mm, which brings convenience to on-site installation.