Modbus RTU protocol parameter

Hi Tom,

The sketch get compiled now.

I have another problem

I want to set the Modbus RTU parameter. in your windsensor example the parameters are set like.

modbus_construct(&packets[PACKET1], 1, READ_HOLDING_REGISTERS, , 1, 0);

modbus_configure(&Serial, baud, SERIAL_8N2, timeout, polling, retry_count, TxEnablePin, packets, TOTAL_NO_OF_PACKETS, regs);
                                                                                // Serial1 = INDUSTRUINO RS485


I want to set  Stopbit 2,parity  none baud rate 9600.

My sensor is giving some float value. so I must read Register 40001

So how to set this 

Please help.


Jagroop Singh
Jagroop Singh
| 2 1 2
Asked on 8/22/18, 11:37 AM

Hi, if your sensor gives a float value, then you probably need to read 2 16-bit registers and combine them to a float, see

But first you have to find those registers; if your doc says address 40001 then start looking with 

modbus_construct(&packets[PACKET1], 1, READ_HOLDING_REGISTERS, 0, 2, 0);

That means: slave register index 0 for slave address 40001; 2 registers to read; store in master index 0 (and 1, as you're reading 2 registers)


| 1 1 3
Answered on 8/23/18, 12:57 AM

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Asked: 8/22/18, 11:37 AM
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Last updated: 8/23/18, 12:57 AM