Examples to read uint32_t 32 bits modbus register

[legaxus]

Hi,
Appreciate if you could show examples on reading uint32_t 32 bits modbus register?

[Alexander Emelianov]

Article

[legaxus]

uint16_t res[REG_COUNT];
readHreg(SLAVE_ID, FIRST_REG, res, REG_COUNT);
from the modbus library
so it will be something like this
firstvalue = res[0]
second = res[1]
then combine?

[Alexander Emelianov]

union f_2uint
    {
        float f;
        uint16_t i[2];
    };
f_2uint raw_reg;
readHreg(SLAVE_ID, FIRST_REG, (uint16_t*)raw_reg, 2);

And probably play with byte order then.

[legaxus]

union f_2uint
{
float f; <-
uint16_t i[2];
};
f_2uint raw_reg;
readHreg(SLAVE_ID, FIRST_REG, (uint16_t*)raw_reg, 2);

if its register uint32_t but not float, so I need to change "int f;" ? am I right?

[Alexander Emelianov]

Sure. uint32_t f;
It was just copy-paste mistake.

[legaxus]

ok, thanks, give a try,

[Niladri Dey]

union f_2uint
    {
        float f;
        uint16_t i[2];
    };
f_2uint raw_reg;
readHreg(SLAVE_ID, FIRST_REG, (uint16_t*)raw_reg, 2);

And probably play with byte order then.

I am trying to use this using TCP.

` // start test
union f_2uint
{
float f;
uint16_t i[2];
};

f_2uint raw_reg;
mb.readHreg(remoteIP, 156, (uint16_t*)raw_reg, 2,cb,9);`

It gives this below mentioned error. Can you help ?

invalid cast from type 'loop()::f_2uint' to type 'uint16_t* {aka short unsigned int*}'