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Topic: Energy Meter Reading using Arduino Uno as Master (Read 444 times) previous topic - next topic

webscada

I am working on a project to read energy meters using RS485 ,The Arduino Uno is to be master , modbus protocol.I want to know
1. Do I need max485 shield or can i connect wires direcly to RJ ports of meter ?
2. How to send modbus holding register commands.
3. can i send command without modbus  library.
4. For example , if i need to read holding register of slave id using the following

11 03 006B 0003 7687

command is requesting the content of analog output holding registers # 40108 to
 40110 from the slave device with address 17.

Then I need to convert  11 in byte 0001 0001
03 in byte 0000 0011
006B in bytes 0000 0000 0110 1011
---

and all become 0001 0001 0000 0011 0000 0000 0110 1011 0000 0000 0000 0011 0111 0110 1000 0111

and then all this stuff using serialport.write method to slave.

Please guide me.


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