mbpoll is a command line utility to communicate with ModBus slave (RTU or TCP).  
It uses libmodbus (http://libmodbus.org/).  
Although the syntax of these options is very close modpoll proconX program,
it is a completely independent project.

mbpoll can:

- read discrete inputs
- read and write binary outputs (*coil*)
- read input registers
- read and write output registers (*holding register*)

The reading and writing registers may be in decimal, hexadecimal or 
floating single precision.