modbus

Do 30000 registers use one word of data? For example a pressure transmitter using modbus register 30001?

I know floating point numbers use 32 bits.

Thanks

The only difference between 30000 registers and 40000 registers is that 30000 registers are read-only while 40000 registers can be written to. Given that, 30000 registers are just as capable of encoding floating point numbers as 40000 registers. So, a single 30000 or 40000 register is 16 bits. If the number you're after is a floating point, you're looking at two consecutive addresses, say 30000 and 30001 or 40010 and 40011.

All 3xxxx and 4xxxx registers use two byte, 16 bit data words, according to the Modbus standard.

However, whether any given device uses one word/one register (integer), two words/two registers (32 bit floating point, or long integer) or four words/four registers (64 bit floating point) depends on implementation.

Modbus doesn't define what kind of data resides in a register or how many registers it takes to get a complete data word, just the size of the register for a given address range.

Most companies use the 40000 registers for every thing. Function Call #3.

You have to have a look at the documentation for the device. Many devices use 2 words despite the standard.