ModbusRtu.h library

Projects Networking, Protocols, and Devices
1

Hello.
I'm using ModbusRtu.h library.
My arduino is MODBUS Slave.
I'm using build in USB port.
It all works.
But....
Everytime I reconect the master (PC) to arduino, the uint16_t registers are reset (they all have value 0).

Is this normal ?

Thanks.

2

Is this normal ?

Yes. If you reconnect the PC to the Arduino it is reset, so all values are set to their compiled in defaults.

3

Can this be fixed using some "no delete on start" function?
The problem is that I use RF protocol comunicating with temperature senzor.
It updates every 2 minutes.
If I restart the supervisor (Node-Red) I've got zerros until the RF refreshes....
In worst case 2 minutes of zeros...

If I will use RS485 and pins 1 & 2 + DE/RE pin will the arduino also RESET?

4

Can this be fixed using some "no delete on start" function?

No, the processor is reset by hardware.

If I restart the supervisor (Node-Red) I've got zerros until the RF refreshes....
In worst case 2 minutes of zeros...

The easiest fix is: don't restart the supervisor.

If I will use RS485 and pins 1 & 2 + DE/RE pin will the arduino also RESET?

Of course not. The reset is done in hardware, so if you don't use the USB interface and don't use the reset pin, the Arduino won't reset.