Using Modbus, what is the MAXIMUM level of precision available?
The correct answer is B, 16-bits.
Common Modbus uses two 8-bit bytes for each data register.
2 x 8 bits = 16 bits
To achieve more precision special programming or a specialized version of Modbus is necessary.
Eight bits is less precise than 16-bits; 24-bits and 32-bits require uncommon means to achieve.
Reference: Bella Liptak, Instrument Engineers Handbook, Volume 3 (3rd Edition), Process Software and Digital Networks; ISA, 2002
Modbus transmits over serial lines between devices. The simplest setup would be a single serial cable connecting the serial ports on two devices, a Master and a Slave.
The data transmits as series of ones and zeroes (bits). Each bit is a voltage. Zeroes are positive voltages, and ones are negative voltages. The bits transmit very quickly. A typical transmission speed is 9600 baud (bits per second).
Author - David