Modbus Poll Tutorial
For a new instrument integration with IoT, it is advisable to first read a given set of registers using PC based software to validate Modbus settings of the instrument. Following are two popular software tools used in the industry:
1) Modscan download link
2) Modbus Poll download link
In this tutorial, steps for reading the Modbus instrument using YuDash IoT device with help of Modbus poll is explained (with focus on data type). Following are steps involved
1) Modbus read through Modbus Poll
1a) Interface the given Instrument using Modbus poll software.
1b) A sample modbus register value has been read in Modbus poll and a non-zero value is validated successfully.

2) Mapping of Modbus-Poll Settings to YuDash Modbus

2a) Baudrate and parity settings

2b) SlaveID, register and display type mapping

3) Mapping of Display data types to YuDash Modbus Types
There are various data types (16, 32 and 64 bit) applicable in Modbus. It is important to have correct data type selected while reading the instrument/PLC from YuDash IoT devices. The data types are explained in Modbus Integration guide.
After successful read of register in step 1b, corresponding code in "Type" has to be filled in YuDash Modbus settings as per below mapping:

Data Type for 16 bit integers

Data Type for 32 bit signed integer

Data type for 32 bi unsigned integer

Data type for 32 bit Float

Data type for 64 bit data types
YuDash supports few 64 bit register data types which are converted to 32 bit floating point numbers.
Byte Alignment Reference

4) Technical Notes
4a) Data exchange between YuDash IoT and RS485 instrument

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